hey, i was wondering! theres no text project for undertale yellow to my knowledge and obviously i wouldnt expect you to do it since youre about to have your hands full with deltarunes chapter 3 + 4, so ive been considering if i could handle doing it myself and was wondering if you have any tips for that sort of endevor?
First, before I get into the tips, I'm am SORRY that I took so long to reply; I've been very busy with IRL stuff lately (international travel for family, over a week of fighting illness, babysitting for my brother, etc.), so I've been really neglecting to answer this [and then my first draft got obliterated because I misclicked!].
Now to answer your question and give tips:
To be honest I forgot the specific hex editor I used (so many years ago!) but if you can, it would really help to find any means possible to do things like teleport rooms, alter stats, put items in your inventory, etc. so that way you can cut down on constant full playthroughs, make some moments easier, etc.
Coinciding with the above, try to look around and find the save structure for UT Yellow, that way when you do any kind of editing you'll know exactly what you're doing.
And like the above, a room index helps for teleporting around to help capture really specific dialogue, especially on repeat playthroughs where you really don't need to play the entire game again just to get a few lines of text, especially if it's around the endgame.
At bare minimum, search around for a text dump of the whole game, so that way you can basically check list every screenshot you take and narrow down exactly what you need.
If you can, try to find a text dump that's roughly organized by available route, especially if you can sort out inaccessible text from the text dump (that way you're not wasting too much time trying to chase text you can't normally find without editing/hacking); https://www.reddit.com/r/Undertale/comments/4i231w/spoilers_excel_file_of_every_line_of_text_in_the/
When you get the text dump, copy-paste it all into something like a Word or Google doc, and as you get each screencap you can erase the corresponding line(s) of text, which helps narrow down what you still need and also really helps feel like you're making some progress; additionally, it lets you organize if you feel like you're not encountering certain lines.
Pre-plan your playthroughs so that way you can get as much as you can per playthrough, for example screencapping using every item that you currently can on your first go.
Folder Templates/Copy-Pasting:
For certain recurring elements in the game, such as monster encounters (ACTs, Flavor Text, etc.), shopkeepers, and so on, you might want to have some kind of empty folder (+ subfolders) template at hand so that way you can easily copy-paste the necessary folders rather than having to manually make every single new folder one at a time.
The go-to software for taking screencaps; use Alt + Prt sc in order to take screencaps of each new line of text easily, and make sure that there aren't any desktop icons around the borders (they can be fully underneath though) of the windowed game so that way the edges of the captures look clean and consistent. You might have to fiddle around with some settings for consistent image dimensions and transparency, so take a few test run screencaps to make sure everything's in order.
If you go to Application settings > Paths > Sub folder pattern, I like to use %y-%mo-%d %h-%mi-%s-%ms so that it neatly timestamps each screencap so that successive text is neatly ordered, instead of having filenames that are all over the place.
Screen Recording & Video Player:
Whenever text scrolls automatically, use Capture > Screen recording in order to make a video of said text, and then open up the video in your video player of choice (as long as it allows screencaps and frame-by-frame forward/backward) so that you can screencap the last frame before the text transitions.
Look for support from others! Don't be afraid to ask around for any kind of screencap work (sharing the load) or even just asking basic questions like where a certain line of text might be, any kind of assistance will make things much more manageable.
