The issue I have is that whenI type ~watches in google to find synonyms for watches I only find 2
The tilde operator does NOT expose nearly all the semantic information Google has discovered and is using - not even close.
I would caution you about making many strategic changes to internal anchor text, especially if it's done to affect keyword rankings. That kind of linking really needs to be focused on the user's needs. Once in a while it can help Google find a better landing page for a keyword, but only rarely to obtain ranking for keyword that was not previously ranking.
Too many changes in this area seem to raise the alarm for Google. An occasional change can work out well, but if that one success stimulates LOTS of similar changes, then you can get into trouble.