I have somehow discovered the trigger and the workaround for this “critical internal error” crash.
This usually occurs when there are deeply nested activities such as nested for loops with if else.
The behavior is when you scroll down to the specific sequence that is “corrupted” it loads a bit and will crash. So my temporary workaround for this is to collapse the sequence if you can without triggering a crash or collapse the parent sequence and then move this sequence outside the deeply nested loops or outside the main sequence and then you can expand it safely without crashing. once you are done editing your sequence make sure to collapse it and drag it back to the original sequence. Never expand the corrupted sequence or it will trigger a crash.
Its a very painful and annoying bug but the lesson here is to optimize your code and avoid using deeply nested activities which may trigger this and use invoke workflow instead as best practice.