The function sf::Transform::Combine() is a little bit misleading in my opinion. It makes the impression as if the result is stored in *this, and not returned as an independent copy. Additionally, the documentation for Translate() says "Combine the current transform with a translation", where the term "combine" is used with semantics different from the Combine() method.
Other functions returning copies like GetInverse() are also named differently, maybe GetCombination()/GetCombined() would be more intuitive. Or you only provide Combine() which changes *this. Or a global function. Or you don't provide it at all, as the same functionality is already covered by operator* and operator*=.
I don't know what other users think about this, maybe I'm the only one. It was just something that took my attention.