Generally, ORM's try to present a high-level abstraction of your data and data model than the engine does natively.
That makes it the ORM's responsibility to implement the abstraction in a good way. Problems come in when the "good" way depends on factors the ORM doesn't consider or expose well.
I actually mean transpiler in a mainly syntactic sense, and would want it to avoid higher-level abstractions (after all, as you point out, ORMs have that ground covered).
While that is closer to ORM in the classical sense, the modern use – and why I used 'oft referred to' – is more accurately a query builder, but get called ORM regardless. The reason people reach for this type of tool is because there hasn't been a good solution to this with SQL proper, necessitating another language. Until now.
That makes it the ORM's responsibility to implement the abstraction in a good way. Problems come in when the "good" way depends on factors the ORM doesn't consider or expose well.
I actually mean transpiler in a mainly syntactic sense, and would want it to avoid higher-level abstractions (after all, as you point out, ORMs have that ground covered).