There’s a way to get a charged sweep in a combo wihout having a charge to start with.
If you call casshern right as you hit the opponent with a :d::snkc: and immediately cancel into charge, you will be able to link a charged roll sweep after the charge and it will combo. The timing is really tight.
You can also cancel into heal instead of charge and it will be safe. Using heal shortly after calling casshern will result in casshern being healed. Waiting a bit and then using heal will result in roll being healed. It will be safe either way.