Interjecting, I think it's a great idea to try to find the most
friendly, effective language to draw people in that we can get. Wish I
had expertise myself to help out, but, alas, writing short has never
been my strong point. The idea of bringing in community feedback on
mobile language is an interesting one. :) We have all kinds of
expertise out there, although finding it can be hard. Obviously, we'd
just have to be clear that we're bringing in advice from multiple
streams, so that people aren't disappointed if the ideas they propose
prove unworkable for some reason, such as if they are not accessible
to ESL users.
I've been trying to think of any discussions that could be useful
already on Wiki for this kind of thing, but it's such a different
skillset, writing this succinctly.
In terms of copy-text experts, there must be somebody out there who
teaches people this stuff. Not sure how easy they are to find, though,
or if they'd be in budget.