It’s too late for today, so the program is untested. I’ll probably test it on my calc the other day when I got more time to waste.
In short, this calculator is extremely limited. Hats off to the contributors at https://algos-casiofx92.com/; you guys are genius.
Note: Access X&Y registers with “Aller a x:y”
The program space is rather limited. Instead of doing I/O the way I’m doing it (by using two registers as the “streams”), you can modify the program to redirect the I/O functions to “Demander valeur” and “Afficher result”. In that case the maximum BF program length is 16*5=80 steps.