There are a lot of "what ifs" in that. If the stars aligned and it was actually made for any kind of NES mapper though, converting a game to use another mapper is not new.
I really don't think this would be the case though. This wasn't made with the intention to play it in an NES at all.
I'm not going to 'state' what 'can be done' only what might possibly have to be done to start with...
1. The entire script gets pulled out seperately from whatever file its being streamed from... and put into a word document, for 'future use'/conversion. This assumes there is no 'real-time patching' going on just elements being displayed over other elements via whatever trickery the 'vessel' emulator allows. Perhaps something like Mesen does with HD Metroid mod? This of course won't work on hardware...
Example? The main menu/title screen might be a 'graphic' displayed seperately 'over' the original title screen? That would most likely require designing an entirely new title screen and animation to mimic what it does...?
2. Second issue is matter of how one opens and expands the rom to allow for improved scripting methods... The limitations may require the rom to be modified out of its original capabilities... Perhaps it would require switching to another mapper that could handle changes to how the script is handled... Also formating of the text and fonts would have to be taken into consideration (how much can be displayed on screen at one time, how is it displayed on screen); how many 'letters & numbers' can be displayed on screen at any given time? (are there any 4 letter naming convention issues in the original rom that would require to be 'expanded'?)... How are current fan translations handling the issues (and what is their lenghth and limitations on text)? If the ground work is already 'done' in the fan patches as in modifying and expanding how much text can be displayed, and how it displays... Would it work with the new translation assuming it could be 'injected' or would there not be enough space to inject it in the first place... and how much would it require to make sure each line fits where it needs to be injecte (assuming some lines go beyond the current limits even within the fan patches)?