Hello again and thanks for clarifying.
In the context of sterile pouches seal stability - IMO the "significant change" clause is irrelevant. Even seal strength is not too relevant, though it's quite easy to measure and process, and thus tempting

Of course seal strength has to be above an acceptable minimum, but much more important is the seal barrier (sealing) quality. The best way to demonstrate that is via biological challenge (sterility testing) but since it's a bit expensive and complicated, many start off with mechanical tests such as pressure testing (inflating and looking for pressure drops) and dye testing - each has their pros and cons. I am not aware of 1 comprehensive published standard covering this subject in a very good way - what I've seen is a combination of scattered published test methods, in-house developed test methods, and some (creative?) justifications. You could, though, make some good use of ISO 11607 (probably already are).
Cheers,
Ronen.