I was upgrading my stables to level 2, and the cunstruction time is complete, but nothing has happened. Is there a delay for the upgrade after it's done being built?

Thanks in advance!

There may be a lag for several minutes when server is busy with other scheduled tasks.

Oh, thank you!

One other question if I may post it here.

Someone bought a pet that I placed in auction, and about 2 hours later the peson messaged me saying they didn't mean to buy him and asking me to buy him back. They weren't unpleasant about it or aynthing, I just want to be sure that they can't report me for any wrong doing if I don't want to buy back the pet I sold.

Many thanks in advance, Thrace

Players are responsible for their in-game actions themselves unless something happened due to a bug. So no, they can't report you, only politely ask if you would agree to revert the trade. But this is completely up to you if you want to do this or not.