Where should I go next after talking with Rosalind? I have no hint
Also game seems to crash just before the battle with Rugal in his mansion
Go out of the abandoned mansion, if you checked the book shop too you'll have the new info about what to do.
Do you have an error report screen? I've checked the battle but have no issue (may be some errors with his boss ui but not sure - does not see anything after a few tests).
Edit: got the UI error if using the save from previous builds. maybe that is the issue.