Your two sentences contradict each other. Programming languages decide what parts of the programme behaviour they want to specify, and what they leave to the implementation.

Of course, you can redefine what 'semantics' means to say it's the kind of stuff that should be preserved in a translation. But as I said, different languages care about specifying and preserving different things.

See also how most languages (or their specs) don't particularly care about letting the user specify exact timings of operations.