Heh, just spitballin' :p. Some of these are definitely out of scope for a bug fix project, but the lines can get a bit blurry sometimes especially with Restored. I haven't come across the code for most of these yet, so I can't say how feasible they are either. Some comments on specific items:
When dual-wielding two weapons of the same type (other than bare-handed), it is possible to gain 2 weapon levels in one battle by raising that character's attack counter high enough (does not apply to Restored).
Gaining 2 levels in the same battle is still possible in the Bug Fix patch since it levels up the primary weapon type and then the secondary weapon type. For Restored, I converted that section into a loop over each weapon type, so the same weapon type never has a chance to level twice.
Update the status (/equip, but more work) menu screen to display magic penalty, armour resistances, attack elements/families, and weapon special effect.
Most of the plumbing for displaying spell penalty is already there, but the others will need a little more code and probably some icons.
Let multi-target Life/Esuna target dead characters.
Another consideration is that multi-target Esuna works on targets with Blind/Venom/Curse/Amnesia/Toad, but skips over targets with Stone/KO, which is a bit inconsistent.
Use different battle messages for Flee failure when the battle can't be escaped vs. when the character failed their success roll.
This would be based on the flag for whether a battle is escapable or not. I haven't gone looking to find out what sets it, but I think I've seen it set for more than just boss battles. Assuming the battle is escapable, the only way for fleeing to be guaranteed to fail is for characters with 0% evasion.
Scale stats for new characters to average party stats?
I was also thinking about Leila and Gordon; they rejoin in almost the same condition they were in when they left, except with their ailments cleared (leading to the bug where they can be alive with 0 HP) and being set to the back row.
Evasion/Magic Resist levels should probably have a low cap, as it is currently quite easy to become effectively immune to physical attacks and spell successes by casting Blink/Shell.
Damage spells are one thing; immunity to spell successes won't do more than halve the damage, which still seems fair. One good Shell cast can also render your party immune to negative status effects (other than KO, of course). But yeah, high evasion levels are more of an issue in terms of balance.
@abw: How would you feel about, assuming it's possible and not simply tied to an inflexible room data table, to change the BGM of Fynn Castle post-liberation to the Rebellion Theme used in the hideout? It seems bizarre that it would still play the eerie castle dungeon theme even when it's occupied and the headquarters for your entire operation. The PSP version retained this, though it feels a strange stylistic choice.
Hmm, yeah, I guess that makes sense. Plus, is there anywhere else you can go post-cyclone that still plays the rebel theme? At least Deist still has the castle theme if you want to hear it some more.
Also a minor downside to the passive skill growth patch in Restored is that Warp loses some of its functionality much earlier, since it would only level through use before.
I agree that auto-levelling Warp is a mixed blessing. There's also a risk of levelling all of your spells so high that you can't cast any of them, but you can always buy a new spell at level 1 and cast it a few times to gain max MP, so I'm not really concerned about that.
Are there supposed to be encounters in these rooms even before you liberate the castle?
Maybe? I haven't looked at any of the map data myself and don't have much to say here!
So, it looks like reviving dead monsters is broken in several places. Assuming you succeed in reviving a monster, its graphic doesn't reappear, the number of remaining monsters isn't incremented, and it becomes untargetable at the end of the round (but you can still beat up on it some more until then). The Life spell restores a minimum of 1/16 of the target's maximum HP, but for mosters with less than 16 maximum HP, they get revived with 0 HP - you would need at least 10 successes to revive a Goblin with 1 HP! Given those issues, instead of fixing them directly I'm just going to make reviving monsters ineffective as part of the fix for trying to revive monsters that have fled.