It there are valid *A flights you’d have zero chance even if it would be obvious the problems in FRA. During the summer chaos I had one agent at least say she was trying non *A to help me but when I gave her some alternative routings (Japan via Europe) she found a LH/AC combination so I never found out.

its more likely coming back the other way with the EU protections and the requirement to take all reasonable measures but they’ll probably deny it anyway and in a systemic situation like FRA weather there would again be virtually no chance as airlines look after their own disrupted passengers

for personal travel if it’s a must fly /reach that’s why I try to keep a minimum amount of miles across the major programs for a coach ticket at least. For work that’s the travel agent job