He he hey! I'm that Spain native that can bring some light into the Manga Plus translation.
For example, just in the first page of Chapter 1, the Spanish translation of "先輩、お冷どぞ," (Here's some cold water, Senpai.) was "Aqui tienes tu bol de arroz, Momose" (Here's your bowl of rice, Momose.)
I can't talk about what they say in the original because I don't know japanese, but at least in the rest it didn't seem wrong, even if this is an error.
Translating "ごめんけど、私にそういう気はないし…" (Sorry, I don't have those kinds of feelings/I don't swing that way) into "Lo siento, de verdad. No era esa mi intencion." (I'm very sorry, but that wasn't my intention.) is also incorrect, no matter how you spin it.
Okay, this is right in the translation because you need to check in the context and, if you read the whole page, it's more normal for a spanish speaker (at least if you are from Spain) what Momose is saying. She is saying sorry for the way she talked about that kiss. It would feel reeeeal weird if she had saying something about that she doesn't swing in that way, even if that's what she says in japanese. It just doesn't feel normal in spanish saying it, it's better the MP translation even if isn't exactly like that.
In fact, if I have to say something that doesn't feel right, it should be what Shimizu answers xD not what Momo is saying. That "creo que, si fuese así, sería muy feliz" = "I think that, if that would be like that, I'll be happy".