Catalyst Theater’s production of The Flu Season is something you want to like. You’ve got a small, scrappy theater company taking on a complex, ambitious work. There’s a fine cast assembled, and its purely functional set contrasts nicely with its fantastical backdrop of abstract, stormy trees. But attributes aside, it comes down to the fact that, as a play, Will Eno’s work is just a little too pretentious to be enjoyed. The work takes place…