The reason the rehearsal mark paragraph style doesn’t change when you change the overall font via the Music Font dialog is because it is set up to override its font, which isn’t really right, and which we will change in a future version. This isn’t something you can change in Dorico for iPad, I’m afraid, since it doesn’t contain the Paragraph Styles dialog. If you don’t have access to Dorico Pro on the desktop, I’d be happy to fix this for you in your project if you want to upload it here or send it to me via a private message.
As for the crash you’re experiencing, I’m unable to reproduce this, but if you’d like to find the crash logs from your device, I’ll be glad to look into it further. You can find them by going to Settings > Privacy & Security > Analytics & Improvements > Analytics Data. They will have names like Dorico-2023-02-12-115959.ips. If you can easily share them to a computer and zip them up and attach them here, that would be great. Otherwise you can share them with me via email: my email address is d dot spreadbury at steinberg dot de.
In the meantime, have you considered trying the jump bar itself for navigating to rehearsal marks? If you tap the Go To tab, you can then type e.g. ra and hit Return to go to rehearsal mark A. (It’s r followed by the letter or number of the rehearsal mark you want to go to.)
Thanks for the crash log. Unfortunately there’s no Dorico code in the stack: the crash appears to be entirely in the netherworld of iPadOS and the Qt framework that Dorico is built upon. However, I will talk to my colleagues about this next week to see if they can make any sense of the crash log.