Coordinating conjunctions between different pairs that are close to each other

1. suggests that {I can play} the piano, the guitar, speak Russian. It is as if speak Russian were a noun phrase, the object of play. This makes no sense.

2. {I} can play the piano and the guitar is one concept saying what {I} can do. The added concept that {I} can speak Russian is a second concept of equal status, so needs to be separated by a comma: {I} can play the piano and the guitar, and speak Russian

The second version is therefore acceptable with the addition of the comma.

I have used {} to indicate the common links to the italicized concepts. Apologies if this seems a little awkward.