I know I'm quite late but thank you so much for this! 😭💘
As for your question, if I do get the privilege to have an anime song be played in my wedding, I'd want a piano and violin version of "Sayonara Solitia" by Chibi Saeko. I have always loved listening to this song. I even made a cover of it! You can check it out here.
I know it's a sad song and the lyrics aren't meant for a wedding event, but I just believe, and I pretty much imagine it right now, how beautiful for this song to be played in a violin and piano on a special day like your wedding day. I just love how the chords and the melodies come into color.
It's truly a very nostalgic feeling. I remember vividly how this song comes popping up after every episode of Chrno Crusade. HUHUHUHU I just love that anime and this song. It breaks my heart, but in a very good way. 😭❤️