I think all of @poetryandwine 's post and others are bang on, and agree the actual experience of studying your subject abroad in local language is fantastic with all the experiences it brings, one does need to think twice about the challenge if it affects final classification and the impact on study programme.
My DD is currently on her YA, not studying STEM and thankfully needs just a pass/fail (though her conditional grad offer is dependent on maintaining a transcript level consistent to Years 1 and 2).
Her feedback - unless the course consciously responds to its cohort mix to include non native speakers, then no allowances are made to be inclusive, slow down or even acknowledge the non-native). Her contact hours are high, but she finds the modules lack teaching lustre and it takes a strong student to stop the lecture for clarification because of gaps in understanding. Zero allowances made.
She manages due to being a strong language student who has also tutored GCSE/A level for over 2 years so she says she is just about coping vs others. Her hardest area of study is Arabic, taught from Spanish base vs her university and Middle Eastern semester approaching study from English to Arabic. Double brain fry as she calls it.
But the overall experience (for her) has been tremendous, and she believes has helped her to secure her summer internship so has been worth it.
My suggestion, finance permitting would be to take summer intensive instead. The level of entry is assessed. She'll get to be around other HE students (many from US and other international institutions as part of their programmes of study, UG and PG) and still get to socialise/play with a 25 wk intensive programme across circa half days, win win. DD came across students from all areas of study when on her intensive in 2020, not just humanities; the idea of combining STEM with language is sound (Imperial has some great STEM combos with Spanish), I can't comment on the Bristol offering with their partner universities.
Do make sure your DD does do her independent research if she proceeds, an agreed academic sign off between the two isn't enough to cover the detail of delivery, how marks are collated etc etc. And quite often there are timetable clashes, caps on modules/student numbers etc that only get dealt with on matriculation that can alter the programme make up for the incoming student.
Good luck to your DD on whatever decision she makes!