This seems to be another issue, them. For the situations that the suggestion has a wrong agreement in the sentence after being 'corrected', you can add a rule that verifies that situation.
I imagine, it will be very tricky to make a rule that identifies the word cases, but that would be one way to go.
There is a workaround I use. Sometimes a rule provides good advice (right direction), but it isn't perfect (as in your case, missing word agreement). After the first correction, another rule picks up what is missing and fix it as well.
Works better on LO and the standalone tool, since, in the online tool, people will have to check the document, at least twice.