Man what a shit weekend I had.
Sorry about not posting.
Now back on track, wow you guys surely have some interesting points.
Let me get back to some of them:
Bagu retranslated as Bug. Yessss? 
This is one of the first re-translations I was gonna make

I want to keep both the Error guy and Bagu, but Bagu will have his proper english name of Bug.
I mentioned in the other thread to rework lives. Each extra life is added to the max total and not the current total.
This is something I am thinking to implement, however from what I've seen, the game does not save the amount of lives into SRAM at any point, so I have to see if I could somehow make the game save the maximum amount of lives into SRAM and then add +1 to that lives counter for when you find a Link Doll at any point.
This might require some heavy ASM hacking, and SRAM hacking too, which I am a noob at, so it would be tackled down the road to see if I can do it. If someone could help here, it'd be greatly appreciated.
https://ibb.co/idgGNx actually something like this would look even better, and maybe if you implement a sword upgrade or 2, just add sword icons (or a sword that is hilt on the left and a growing blade as it gets powered up)
although this, looks good as well. but i think it uses too many colors? (because black has to count as a color, idk) https://ibb.co/kKSO2x this is actually what i would prefer. giving all 3 stats a uniform look. the little L under Life and the little M under Magic is so redundant anyways,
also, if you could add the message in text when pause "press Up + A to save" would be really cool!
That's a really good mockup!
But sadly I still need a colour to overlay the Health/Magic consumption bar.
So that means I need 3 colours for the HUD, one which should be white for the letters, one to mask the consumption effect, and another one for the hearts. So this really doesn't leave any room for the green colour at all.
Either I go for a whole black to cover up the red/white bars (consumption) or change the overlay from blue to green, but it doesn't look pretty. So I am stuck with either leaving the Blue overlay or either making it black completely, but the sword icon won't look good. xD
One more thing, is that I haven't tried to flip around or reorganize the order in which the Sword, Magic and Health are displayed/printed in the HUD.
@IAmCaptPlanet
That's a great look and the green hilt is fine, if this all would work.
As far as Bubbles go, I can see the farming concern because they respawn easily unlike many of the other high xp enemies. I was gaining xp at such a rapid pace that I personally didn't feel the need to farm them, but I would be ok with taking their xp down to 20 to match the Ras.
Well I didn't really see it that way to be honest.
In the first palace you encounter Red Stalfos, which are really easy to kill (go down in like 3 hits I believe) without any effort but simply ducking and stabbing their feet. They give out 30 Exp.
Now compare them with the Bubbles which require around 10~ or so stabs and they give 50 Exp, and I think the comparison is valid if you take into consideration other sword/shield based enemies in the 1st Palace.
I think the damage dealt to them is now way more in balance to how many hits they took to kill them, and at the end they just give out 50 Exp, which is kinda lame compared to the amount of stabs given out in the original to kill them.
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@SCD sorry I didn't get back to you before.
Let me address your suggestions:
1) Restore the roar sound effect from the FDS port.
Would this be for the Game Over screen or the bosses roar?
I kinda like the Game Over screen sound of the NES one.
Though I can't remember if the NES used any sound for the bosses at all.
2) Make the level system behave more like the one from the FDS port.
How exactly did the level system work for the FDS port?
For what I know, the Level system is way more user friendly in the NES, isn't it?
3) Rename the Trophy & Water of Life back to being called Goddess Statue & Holy Water once again.
This will be done for sure when I tackle rewriting the script.
4) Restore the Dragon Quest reference in the cemetery from the FDS port.
This is one I REALLY want to do, but the NES port completely disabled the text prompt in that particular place in Saria.
If someone knows a way to re-implement this into the NES port, please let me know, as I'd really love to see this one back in the NES one. The text I will be going for (if this gets implemented back) is "The hero Erdrick rests here"
5) Restore the water movement from the FDS port:
This is one I want to put back in as well, but I haven't really researched enough as if it is possible to achieve or not in the NES port.
If someone has an insight or knows how to do it, please let me know as well.I
think this will require modifying the mapper of the ROM.
6) Restore the unused windows for both the Maze Palace & the Hidden Palace:
This I might do as well, the windows look neat enough to not have them there

7) Restore the FDS sprites of Carock, Kidnapped Child, River Devil & Volvagia:
I think that from all of these, I might only end up doing the River Devil.
Carock and Volvagia's sprites look better to me on the NES release, and the Kidnapped Child has a purpose.
In the original FDS game, the Child's sprite had some sort of multiple ropes which tied him up, and you had to stab it with the sword to free him. However, in the NES release, you can simply pick up the Child, which makes the need of the ropes useless anymore as you don't remove the ropes now.

Restore the FDS version of the King's Tomb, but add the unique statues from the NES version on both sides of the grave like this edit that I did:

The mockup looks really cool. Though I'm still unsure about this.
I don't know if this will affect something in-game or not. Is visiting the King's Tomb necessary for progression in the game? I can't recall right now, it's been quite a while since I last did a full playthrough of Zelda 2
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So right now this is in the TODO list:
- More common enemy drops (in general)
- Reduce beeping noise to make it less annoying
- Change in-game text to something better translated/localized. This is a good base to work with for that: http://www.glitterberri.com/adventure-of-link/retranslation/
- Rebalance enemies. This might take a while to do since I need to know WHAT enemies and HOW to balance them properly to give a proper balanced experience and not a too easy/too hard one.
- Try to add a PAUSE message on the overworld (this is really hopeful lol)
- Try to restore the Dragon Quest reference
- Try to restore the moving water animation on the Overworld