Hello Renaud !
I was wondering if the vectorial map will allow the GM and players to import some pictures to replace the characters pawns or make movable furniture? Even though it might not be a priority, do you think it could be worth considering doing it later?
Some sites like OpenGameArt.org could be reliable a source of assets for this or whatever kind of pictures you might need and you would not need to worry about copyright.
Edit: Just found your spreadsheet. I guess "Add avatar selection into new character dialog" may be what I was looking for?