I would want to know how synesthesia is diagnosed. It’s not that unusual when some of, say, audio input or output represented also in the kinesthetic or visual mode. Sub-vocalising is in itself is a kind of synesthesia, we imagine the kinesthetic sensations in the mouth and throat that are connected to particular sounds of our native language or a well-trained L2.
Wiki (rus) says (what’s strange really, and really raises questions to the article) that audio-kinesthetic kind of synesthesia is one of the most rare kinds. It isn’t true, it’s a requirement for performance on musical instruments, for example. You just can’t get by without it, because it develops automatically. Sound-engineering also requires this type of perception.
The article is vague a little. It also claims that from the mid XX the interest in the phenomena has decreased.