STEM in local languages already exists as an option. But IMHO, it will be a backward leap because even for basic vocab, we nowadays have hinglish or other such language blends. And as a result, folks know what axis is but not what dhuri is. Or what cell is but no what koshika is. Or what machine is but not what yantra is.
In both cases you need to learn the lexicon, the technical jargon, anyways. So its not as if studying in local language will mean they didnt need to learn new words.
Also, most books, and as you reach college level, most research papers, are written in English. Its a bad idea to actively train our kids to avoid understanding this knowledge repository. If understanding is the problem, train teachers to explain in local languages. Once you explain someone a concept with English jargon but in local language, even if they are not adept at English, they can still understand it better. Technical writings in English are straightforward, you don't need a high level of proficiency, its not English literature.
By the way, I don't know what "Logic" as a subject is meant to be like. Is it like teaching students critical thinking or is it like Model Theoru in maths?