The last update included this detail, which gives players insight on what heroes were used in Guild War including today's matches:

"In Guild War > player's Season Log, you can view details such as Heroes used and battle results."

I had pressed the arrow in a tower's guild war history and exited out and came back, and it's a little buggy.

When you look into someone's attack history, you're unable to switch to viewing their defense history, and vice versa.

You'd still need to gauge opponents' stats and artifacts; but this is great information for people who use their guild crests early.