I think TI has a mod guide though I couldn't tell you how good it is per character...it seems to be an overall good guide for what mods to farm and who to equip them on.
"Everything is proceeding as I have foreseen...mostly"
There is one in the "guides" section that is per character. Some of them I don't agree with, but it's a good place to start. And the point of mods was to make characters work how you want them to, so some disagreement should be expected.
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https://forums.galaxy-of-heroes.starwars.ea.com/discussion/64603/how-to-mod-any-every-character