Often. On the other hand, sometimes the entire reason a succession occurs is because something was wrong with the last regent, in which case keeping the treaties might provoke more outrage...
Sounds like a forced regent changed in this case due to critically low legitimacy, so should be similar to rebellion.
If i recall Alden of Helna, after claiming the throne decreed he sought an isolationist stance, and as such seeking to renegotiate or break most foreign diplomatic ties.
Which was then muddied by Alden conforming to various previous agreements without any statement for or against it, but he certainly seemed to expect others to be bound by them when it suited him.
So while SWT took that to mean "Business as usual", Alined took it to mean "No more alliance" and that was partially down to interpretation of clauses in the agreement which allowed SWT to recognize Alden as legitimate, but did not allow Alined to do the same.
A lack of formal decree on the subject (aside from the isolationism decree), and an erratic behavior, did not help things.