“I think best would be extremely simple. That crimes should be recorded according to the person's sex at birth and not by self ID gender identity.”
I think it should be recorded as biological sex (at birth) only. Not self ID, and also not even transgender identity if someone has a GRC - as they are still 100% biologically male sex (their gender identity as a TW could be also recorded to ensure their special status is recognised/keep the criminals and their supporters happy.
Nothing subsequent to birth sex matters when it comes to the characterisation of 1 group from another according to relevant statistics. The only useful, true, unambiguous and relevant fact is if they are biologically male or female.