There is a third potential factor in the high rates of TW imprisoned for sexual offences.
If someone commits a sex crime that doesn't result in murder, there is a witness (or witnesses) - the victim. If that victim gives a description, then a description of the offender as 'male, brown-haired, mid-height' would be next to useless, where as a description of 'man dressed as a woman, brown wig, mid height' would narrow down the search pool considerably.
So if 1% of men commit sex crimes, maybe 10% of those get caught, and if 1% of transwomen commit sex crimes, maybe 80% of them get caught. This wouldn't apply for crimes such as theft if there are no witnesses.
I have no idea if this is actually the case, I'm just musing.