no clues. This is the problem: The ressurect powder and the scroll work fine on
the other characters when they die. My priest is dead and everything I try gives me the answer "no target within item range." I have tried every combo I can think of and the priest cannot be seen or found. But the priest is in the group and on the main screen, showing the skull (dead). He does not show up on the party formation list. But
for a while he was just like the other characters, easily resurrected.

If your priest could be resurrected before and can't now, it sounds like a bug. Unless he's been killed too many times? Surely they wouldn't put a limit on the number of times someone could be resurrected, would they? That's the only other thing I can think of and in a situation like that, you'd think they'd tell you that was what the problem was. Anyway, it sounds like you should send your savegame to Sir-Tech and see if they can help you.

I have almost the same bug while playing the game with a generic memory trainer. I used the trainer to lock all my Party member's health and stamina to full. The problem is that certain spells kill some members outright and some critters does critical damage and took out some of my party members.

So, those guys are actually "dead" but their health and stamina is at full (thanks to the trainer)and I can't seems to resurrect any of them. If this is the same problem as you are facing now, then just get a hex editor and set any of your "dead" party member to zero health.