I set three markers with tempo changes, right on beat 1:000. 75bpm 125 and 225.
Sonar counted in at the new tempo each time.
So yes, if I change the tempo at 10:01:000, Sonar counts in at 145 if I start the project at measure 10.
Just for S&G I tested with tempo changes at 9:04:239 (160) and 10:01:000 (145).
Counts in just fine at both; obviously it counts in fast, then the metronome slows down immediately if I start at
9:04:239 as would be expected.
HTH
T