More fun with grammar checker

So, here's a sentence grammar checker didn't like.

"He didn’t regret what he’d done, what he’d let Jack and Martin do; he did wish they had won."

I dare you to guess what it wants fixed.

It wants "he'd let Jack and Martin" changed to "he let Jack and Martin would".

Yes. It wants

"He didn’t regret what he’d done, what he let Jack and Martin would do; he did wish they had won."

Honestly. "He let Jack and Martin would do."

Words fail me.