On my way to finish Hibike Euphonium's 3rd volume, I think I can safely say that so far the queerbaiting it got some infamy for is mostly intentional anime changes to make already intimate moments lean way more heavily onto the demographic that likes GL content.
On the novels these moments still feel very queer but they also have a very strong platonic element to them that makes them not feel like it needs to develop into a romance or that it wants the reader to expect a romance out of it.
On the other hand the straight romance is even more "by default", where we have a couple with no chemistry at all in Kumiko and Shuuichi that the narrator needs to tell the reader something is supposed to be read as romantic. And the very few moments that do feel romantic come out of nowhere unfitting for both the scene and story.
So it still stings. Even though I don't feel necessarily that it needs to be a GL story like I did when I watched the anime, as the queerplatonic writing for the girls is very strong... man with how no narrative connection the straight romance development happens it feels a lot like a time waste in a story that would be perfect without it.
Maybe that will change if the story starts focusing more on Kumiko herself, but so far I've been getting physically tired whenever Shuuichi shows up.