I have reimplemented @isferos’ idea in Python 3 for a flexible length seed length (12, 15, 18, 21, or 24 words):
It is called with the words that you know as command line arguments and _ as placeholder for words you do not remember.
If the last word of a 15 word Yoroi seed phrase is missing, it will give you exactly 64 possibilities (the last word encodes 11 bits, of which 5 bits are checksum, so 6 bits are part of the entropy and 2^6=64). For missing words in other places, the order of magnitude is similar.
If two words are missing, we are in the range of 131 072 possibilities (exactly this value if one of the missing words is the last one containing the checksum). So, this becomes quite infeasible to check.