A method for making 1 glyph for each word change to a second Stylistic Set indiscriminately?

Hello dear Forum, in the wake of reaching a couple of partners about this issue and getting generally shrugs, I really want to believe that I can track down a response here. My client needs their new feature typeface naturally sub an irregular, normal glyph in each word with an expressive other option. I don’t figure this would work with starting, center and end structures like with Arabic typefaces, nor with a custom calt-Feature (haven’t attempted however, I truly suck at programming). I have let the client know that I can’t actually ensure this prerequisite to be feasible, yet I have planned in two or three extra hourly rates that I would be glad to ignore to somebody who assists me with settling this. Much thanks to you, Max

Thank you

This should help: Features, Part 3: Advanced Contextual Alternates | Glyphs