I don't understand from your post what you are dismissing as propensity evidence.* Disclaimer: We don't know what HCWs evidence is that might link the cases *
At least at common law, what you list above would be inadmissible as propensity evidence.
What you need are facts that are so similar, they link the cases (a so called MO)
So in the HB case, break in to the apartment, the videoing, the clothing, and extended nature of the attack, taken together, increase the likelihood it was the same attacker as the American woman. There is a definite style or signature.
By itself, being the kind of person who attacks weak victims doesn't make it more likely you attacked this victim, where identity is the question.
* Before everyone jumps in - this post is intended only to explain how similar fact and propensity evidence are handled *
That HCW is linking the 3 cases together , DM HB and MM, is irrefutable from his quotes. Therefore the MO must be found in all 3 cases and not only in the two violent and sadistic rapes (for only one of which CB has been convicted). So it cannot be only the entry/exit point that links these 3 cases but something else as well.
what is propensity evidence here?