Are there any ROM hacking discord communities? Most ROM hackers would likely take a look at discord, see that it is another proprietary protocol/client chat program, one in which you can't even make your own servers, and that try to enforce some rules (that they even can kick people off their service, never mind for such dubious reasons, says it all to me) and write it off as another doomed to failure protocol. If you wanted it as a throwaway chat then maybe but ROM hacking tends to be about the long term -- the very game you want to edit is now 30+ years old and being a ROM it has not changed much in that time.
"simply required knowing where to hex edit"
Given you can edit anything you like with a hex editor (you literally have the whole game in front of you in such a case) that does not mean much -- hex editors are generally to be considered very crude tools with limited use. It is not a skill or ability really any more than being able to type is. If you are editing a ROM with a hex editor then you either know what you need to do because you found it by some other means (and even then if it probably wants to only be a simple thing -- copy and paste, something which fits on screen or a couple of scrolls in a reasonable font, adjust width to find a pointer/size table sort of thing) or someone else did and told you (a reasonable possibility someone did it before for Zelda).
I don't know what you want to do with the game so I can't say whether assembly would have been essential or otherwise extremely useful or not for you. Generally for the NES once you are beyond text and graphics, maybe some light level editing, you are in assembly territory.