This is rather inconsistent, but you can either get Romero to the Crypt for Romero skip in around 30 seconds to perhaps a minute. You do not need Obsfuscate etc. just a gun. It may be useful for Gangrel.

I found a link between the AI bugging out and sometimes running to the last known character's spot where noise is made with a shot/crouch, as well as with doors opening/shutting and naturally cutting off AI contact with the player character. So I've tested this a bit in conjunction with one another and found it to work maybe 45% of the time. High enough to warrant some more testing.

Romero also typically will run to the last known gunshot point near the Crypt, so I've found. Just a little to the right from the turn from the slope. I made a video here to explain more on what I mean so that maybe others can work with it/find a consistent method: