I am not entirely familiar with the process or this states case but if they forged documents in pursuit of their legal right to alternative electors... they could be guilty.
If I had to guess though its just more mud slinging with no actual crime of any sort.
Michigan attorney general charges fake Trump electors over alleged 2020 election crimes
They aren't "fake electors." They were alternative electors that needed to sign and attest to their legitimacy as presidential electors in the event the Michigan election results were overturned in court before Inauguration Day in 2021.