Of course! Phoenix tears have healing powers
is probably the worst-delivered line in the series. Rupert Grint is the only one that can vaguely act, from the children.
Not sure if its the delivery/acting or the selection of what to focus on in the films and what to drop. For example in the film Harry finds the diary, reads it once, then it's gone. Why would he get upset? The film is not a telling of a story, it's a series of summarised scenes in some sort of order, they don't hang together well or develop ... anything.
The line you mention does stand out, but I think it's because of the disjointed storytelling rather than bad acting.
Ya'll clearly didn't read it while being 13
I'm still reading it to #1 son (just turned 12), we are on Deathly Hallows. It does help socialise him as he doesn't care for sports/football so he needs to know enough Harry Potter to talk to the other crowd. That said, he does query plot holes and inconsistencies. He's also not a fan of the film.