In the log I saw records like: SELL order replace request… SELL order canceled! … SELL order canceled ! What it means?

These are service records, which are written in the log when you move a Sell order in the betting market. For example, when you want to move a Sell order in the betting window manually or it is automatically corrected according to the strategy settings, the request to move it is made first, then the Sell order is cancelled from the old position and set to a new one.