I would suggest starting with a simpler valueexpression and building up from there so you can see where the issue truly is. Start with the expression itself (I don't want to say formatting isn't possible in a valueexpression, but I don't think formatting is possible in a valueexpression).
0) stop sharing the columns, you'll want to see this result by itself for a while.
1) try: if percent complete < 100, display name and planned completion date.
2) if that works, add the "if duration =0" in front of it and see if that works.
3) then add number of children.
4) then add planned completion date < today + 10 days
If you get stuck on even the basic valueexpression, at least you'll be able to post a more specific question. After you have the basic valueexpression working, move on to putting your concats in, one at a time.
If your concats work, you can try the formatting one more time (again, just try adding one color at a time) -- at this time, I think you may have to make a decision about how important the formatting is, as I don't really believe valueexpressions allow for this (always happy to be proven wrong though).
After you get something working, you can put the sharecol back in.
