String edits not working?

I have a working test mod folder, and attempted changing a few strings (the gametype related things to be precise).
The changes do not show up when i edit the proper language file (ui.dat), but do show up when i replace the string in the gametype file itself. What’s going on?

Edit: I also tried updating the english.big file as a whole, did not help.

Anyone got anything on this?

I have tried literally everything I can think of.
Please someone explain how to make string edits work.