I've been involved in airsoft actively for 3 years. I play once a week, every week, in a competitive environment.
I have NEVER seen a paintball grenade used on the field.
Out of the plethora of airsoft grenades I have seen. Airsoft Innovations TORNADO series, are the best. Hands down. Reliable grenade on the airsoft market.
If you are interested in designing an AIRSOFT grenade. You will find a hard market to follow, although I'm sure AI would like the competition.
If you're designing a PAINTBALL grenade, as you have written, I foresee a lack of help from this community. In my experience, they are simply not used by airsofters in Canada.
Ár skal rísa, sá er annars vill
fé eða fjör hafa. Sjaldan liggjandi úlfur
lær um getur né sofandi maður sigur.