HI everyone 
We’ve just rolled out an update allowing you to see project Custom Fields on your subtasks 
Please check out You can now see and action subtasks directly from your Project task list! for more details!
@Magnus_Ostlund and @sydouma I’m closing out this thread as the update we rolled out answer the vast majority of comments in this thread, but I’d highly recommend creating a new #productfeedback for the feedback you submitted just above as I expect other users will want to vote for these!