I have mostly stayed away from Wikidata for nearly half a year now due to more pressing issues, but I appreciated learning about your concern for the of (P642) issue with respect to lexemes.
As I have been asked to keep my commentary on the P642 project talk page brief and to the point, before posting my reply I eventually cut out some advice that I had just written but wasn't specific to your question. Given your particular linguistic background, which seems very different from mine, I wonder what you think of my approach below:
- Regardless of namespace, when you then want to figure out how to "rephrase" the qualifier in a language-neutral way (to avoid running into yet another anglocentric expression that won't translate uniformly into other languages), I have provided a table of senses of "of" that may help you group similar use cases together.
- Somewhat related to this, I have been playing around with other adpositions (which tend to have several senses each) in the hope of defining a tree of grammatical relations that could serve as targets of item for this sense (P5137) claims.
I'm not a professional linguist myself, and I'm fluent in Swedish and English only, but I enjoy tinkering with dictionaries and translation tools. Does my "grammatical relations" tree make sense (pun intended) to you, and do you think it would work for East-Asian languages as well? If not, could you point out what I need to improve?