authors and cast interviews reliability for fics

A thing I noticed is sometimes some will not care about what the authors say of their work but consider the cast reliable sources. I find this kind of reasoning odd because cast or people working on a media outside the authors won't be told everything about the production and won't know every ideas the authors had too (per example, an author can choose not to tell the twist to a lot of people to avoid it leaking). I'm not sure how reliable Q&A with cast members are too since sometimes, the cast can not answer a question correctly or be biased (same for authors).

While the reliability of authors and cast will depend, I stilll think at least part of what they say should be taken in account when critcizing or writting about a media (the risk with that being people can sometimes take an author/cast interview out of context).

For my ducktales 2017 themed day dreams per example, I prefer to take in account what frank and matt said about what happen post finale if the daydream is set right after the finale, if I do a time jump, I'll still take part of it in account but change some stuff due to the time jump. The show having an open ending does help imagining whatever one want (per example, one can have scenario where donald cruise wouldn't last that long or with webby still able to see may and june/calling them, with scrooge as a dad, I take in account he progressed during the show and that frank doesn't view him as a bad dad for donald and della but I don't have him be perfect since he's still flawed good guy, I have webby keep calling scrooge dad since nothing in the finale indicate she'd stop doing that and frank and matt would've wanted to explore scrooge as her dad if they get the chance so her calling scrooge dad post finale make sence).

I also changed my views a bit since I'm fine with fics changing the canon or what if scenario (I actually do what if stuff)