First thing first, once you get the covers off, put the crank bolt back without the pulley on the align the timing marks. Turn it clockwise.
You will need to remove the crank timing sprocket to inspect the front main seal. If it's bad then you'll probably have an oily belt=replace. If it's clean then it's probably the oil pump grommet.
The t-stat elbows are plastic an the rs's. I wonder if the bolts need to be a little tighter. MAybe the gasket has mushroomed out a bit or cracked. The t-stat might be in there a little cockeyed.
Don't forget to drain the coolant.
Oh and btw, so far I have'nt seen anything that would suggest that the person who worked on it did anything wrong. So far. removing the heads and doing the timing belt does not require removing either the oil pump or the water pump. The oil pumps leak. Subaru has redesigned the grommet already so they know it too.
Looks like a normal subaru with 100k miles.