If you’re RD, and if you can bring the semester grade up to an A minus by working your tail off - and realize that for math and foreign language, that means hours of work daily, since you just cannot cram either of those last minute - then I think that you will have mitigated the damage. If you cannot do that, then yes, I do think that it would possibly have an adverse effect upon your applications to the most selective schools.
Try using Anki for vocab practice for Spanish on your phone. You might find it useful for memorizing algorithms for Calc BC, too, but I think that for the Calc, you just have to do hours of problems daily. Go for extra help as much as the teacher will give you, and try to get a free peer tutor, and maybe professional tutoring, too.