Romanda unswore the oaths and then reswore them, right? So, there's no reason to think that the effect on her lifespan/age would be any different, in the 2 cases. Since she was still alive before she unswore, she should still be alive after she reswore, with the same remaining lifespan in both cases.

So, I'm not sure that tells us anything about what might (or might not) happen to Mesaana.