I have had to use SVGA fix in Keen games to get stuff to run without visual glitches...
And as far as topic title goes, I also had an issue with strange L chars on my ET4000 card and a while ago I ended up hacking the ROM with my own font :
The attachment IMG_2378.JPG is no longer available
The attachment IMG_2379.JPG is no longer available
The font got tweaked a bit more after the photos were taken. One thing I discovered was that there were a row of characters in the ROM that were used to override some chars in the main set i.e the zero in first pic, mine had a line going through it rather than a dot in the middle and couple other chars weren't what I made the such as T and Z).