When I was trying to get ready for Carpo I tried to buyout a scheme, but it placed as a bid. Next I tried to buy a seed from the store but it wasn't  in my warehouse but my money icon said I have spent 5,000 coins. I checked my records to make sure I haven't spent it on something else, when I checked it said I spent nothing.

Your reports do not log the actions that happen before your very eyes. It's only for the things that happens without you knowing about them, like someone buying your lot, using a breeding offer from your male or overbidding you.

Placing a bid means that the amount you bidded is on hold and deducted from your reserve. If you win an auction, the lot will be transferred to you. If you lose, your bid will be returned to you when auction ends.

It's also not possible to buy a seed in the store, so probably you mean player driven auctions and bidding here too.