For conclusion sake - developer of said Spanish fan-port, along with the (possibly) very last release of it:
https://www.youtube.com/watch?v=-yRuizOkmhoBasically, as much stuff as possible was manually ported into the Unity engine, and it seems the developer ain't gonna proceed any further with this one (let alone insert/overwrite English language assets)
And since even XDA Developers users haven't bothered with it (modding Unity program files isn't impossible, but still somewhat cumbersome, even after years of fan-modder R&D IIRC) methinks this port is left in the dust, not to mention superior experiences are now available via Steam Deck and/or Steam Link
Or, funnily enough, (not to mention still being modded way after the official EOL), so one can try hacking away and cross fingers
Windows is shutting down