Depends on (1) whether paying an invoice that includes expenses is criminal and (2) how Trump deducted it on his taxes.
The proseuction has talked about Cohen's taxes but not Trump's. They've said the the crime (if any) would be helping Cohen cheat and that would be difficult.
You are proving my point: People spend time digging for a posisble crime.
At this stage, the prosecution's legal theory should be clear.