Hi @Lefort_Stephane. Welcome to the forums.
You can create custom dice using the built in language. As an example, in the system that I play, a d20 is used for determining hit locations. The table is:
3-5: Right Arm
15-17: Right Leg
18-20: Left Leg
Here is what the code looks like:
!(1d[Head,Head,Right Arm,Right Arm,Right Arm,Left Arm,Left Arm,Left Arm,Torso,Torso,Torso,Torso,Torso,Torso,Right Leg,Right Leg,Right Leg,Left Leg,Left Leg,Left Leg])
I hope that helps.
You can also find more here: https://help.astraltabletop.com/dice/syntax/
P.S. Please edit your post to take it out of the “Feature Wishlist and Ideas” category. Not quite where it belongs. Thank you!