Sounds like you got the answer, but just to follow up:
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Left is your original (at the keycap size) and right is (quickly) adjusted to their min line thickness of 0.012". But as you can see, your islands are smaller than the 0.020" min island thickness in several places, most notably around the G. You could simplify it more and get close, but it's a crapshoot on how clean they'll be able to keep the plastic. The edges, corners, and lines will look good I'd guess, but you certainly don't want the G bleeding into the lines. And it's hard to make it much smaller without collapsing on itself.