How about a macro where you make splits at all tempo markers on all midi items and have those midi items ignore tempo at items start? It would be like a tempo editing mode.
Then another macro to heal all splits aka leaving editing mode.
But that might take ages, it could be hundreds of items, and some of those items could be layered with takes so you wouldn't want then glued.
Tempo mapping has come a long way with your recent sws macros breeder, if we could beat this midi problem that it was fool proof, man that would rock
Edit: or a macro where only selected midi get the treatment.
Edit: each time there's a new pre release, I look for "Midi items now obey track time base"