Fatal Exception: NSInvalidArgumentException
-[NSTaggedDate key]: unrecognized selector sent to instance 0x__

NSTaggedDate is a private type. From what I read on-line, is is almost certainly a memory management issue, where a pointer is referring to a memory location now occupied by a different object. There is one place (in resetKeyLabels) in Keyman engine where we use the 'key' selector to attempt to retrieve the key from a KeyView, so I'm guessing that is the source of this crash.
The call stack looks like this, but (currently) we don't have the symbols available for the Keyman engine code, so it's not very helpful.