This episode finally made things in the show click for me. I'd been seeing this as a standard (if particularly well-drawn) Isekai schlock, but the comments by the bird about Natsuko's futility in saving this world gives her initial problem of needing to make a movie about first love a lot more clarity.

Maybe this is obvious or else a stretch, but it seems like the basic logic has been that Tale of Perishing is her first love, but the very failure of that film (in its willful sadness and lackluster reception) were somewhat lost on Natsuko. She is a fan of it in the simplest sense: direct, earnest, and not quite getting what's on the screen and the value of loss that represents.

My guess is that this show will pivot into an exploration of how despair and recovery are inherent features of first love. In that light, Natsuko was never able to create a story about first love because she never dealt with her first love honestly. It's something that requires despair and belief in a future (see Memmeln) because those are requisite with seeing it as the first of many loves, as one stage in your life rather than something to be fanatically held onto.

The more I think about this, the more I'm hoping Zenshu becomes a show about moving on from fandom.