The way JStudio/Raptor handles texts is very interesting : it draws it on a dedicated full screen sprite

No need to use 1 sprite per character or to print text each frame.
You draw it on a sprite, the OP draws the sprite every frame.

Want to delete it ? fill it with space OR call cls().
The only drawback is that cls will fully clear the sprite...and that sprite is also used for particule (not tested yet)

Well, not that a problem in fact.... 

The only question that remains is Which font could I use ?

JStudio comes with 3 fonts
- 8x8 one
- 8x16 one
- 16x16 one

Note: I was unable to use the 16x16, waiting for feedback to my questions on AA
It seems the problem was me : it works like expected

I tried to add one but I didn't work.
So the only way I found was to edit the default font.
I didn't remove the existing one, I just
- added a new line of 8 pixel height, of course)
- print the ASCII characters 32 to 127 on this line with a bitmap font, size 8
- save

and use with

jsfSetFontSize(0); // use 8x8 font library
jsfSetFontIndx(2); // use font 2 of this library