This is a simple script solution to synchronize small address lists between Mikrotik routers. It is limited by the fact that there is a 4096 byte limit for variables in Mikrotik Scripts. I have maximized the number if entries you can sync by putting only the list name and address in the file
One of the problems with Asterisk, is that, when you blind transfer a call to an internal extension, and the remote side never answers, the call does not automatically go back to the caller. The following piece of dial plan logic should replace your normal internal call logic.