Some notes

Being busy with real-life sadly didn't let me work on GL6 very much, but I didn't lose sight of this project.

According to

https://www.woodus.com/forums/topic/37655-an-even-more-english-translation-patch-ps2-itadaki-street/

it should be possible to create a custom variable width font section:

I made the new font (it's Alps, the same font used in Fortune Street Wii). The guy who's helping me used the space taken up by dummied out test map data to write a whole new text writing routine that's variable width. 

If i interpret this right, it's possible to point the function to draw text to a different point in memory and create a variable width font that is the same as GL5.
No idea how to do that but it's good to know that this seems possible.

Also, i found this little gem that could help figure out how to look into the memory of the game, using PCSX2:

https://reverseengineering.stackexchange.com/questions/21346/translating-a-korean-exclusive-ps2-game-hangeul-encoding

Thinking about this right now, I think the guy who did the undub of GL5 used this method to place the audio files somewhere else in the game and just pointed to that position.
i think in his Readme he was talking about getting help of a bored MIPS hacker to accomplish that.

So, copy and pasting the font files from GL5 to GL6 does indeed change the font, but the font width is still stuck in the same length.