SQL actually isn't all that transferable, because in practice you almost always use an ORM or a query builder instead of writing queries directly into your code

SQL actually isn't all that transferable, because in practice you almost always use an ORM or a query builder instead of writing queries directly into your codebase. So when switching languages you still need to learn the new language's ORM; your knowledge of the underlying SQL will only go so far. Of course queries should be human-readable, but there's no need for it to be a complete language with its own grammar and templating via prepared statements. The queries could be encoded in JSON or some similar (probably custom) human-readable language that can easily be generated programmatically. MongoDB does this IIRC; it's probably the only thing I like about Mongo, but it's a good idea.