Hey celestian. I'm actually going back to your original extension to check that for my next session. The short answer is I don't know if it occurs with your original extension as I haven't tried it in a while. As to your other questions, for the blood splatter extension, the script error occurs only on the players side and not all players, just some players. I enable the health bars on player tokens only and the health "dot" on the monster tokens. I show ally health effects as icons but have this off for enemy health effects. For "view-health" non-ally I use "status" and for "view wound categories" I used "detailed".
I'll try this again with your original death indicator extension and keep you posted. Not sure if I'll have a chance to run a game this week or not. If I don't, I might see if someone can jump on my table and help me check. Thanks again for a wonderful extension!