Paint-stripping purgatory - stuck in the middle - what should we do?
Given the high likelihood of lead based paint, I would not under your current circumstances attack this with a grinder or a sander. You'll create lead-contaminated dust which will haunt you for a long time. Doubly so if any children come into contact with your house. EPA pamphlet here: EPA RRP

So, it would seem that you can either remove and replace the painted wood with new, or continue stripping safely.

New casing and baseboard is pretty easy. Windowsills less so. Door jambs way less so, though that would also get rid of the pesky issue of stripping the door.

Stripping-wise, you might need to let the stripper work longer, or change to a more noxious product. (I'd still go for the noxious stripper over the lead dust any day of the week.)

(edit: forgot to mention heat guns... If you can find a heat gun with a regulated output and know for a fact that it isn't over 1100 degrees F, a heat gun might help.)

Good luck! And by the way, there's no shame in starting a project and discovering surprising obstacles.