Hi
Yes, that is correct.
The statement can only be updated once the event (market) is settled. If you delete a market before it is settled, the statement will not be updated.
Ideally, all markets should be settled from bf. The software provides you with a simulated settlement mechanism for testing purposes, e.g. for use in long term markets, but you cannot use the simulator at the same time as actual settlement from bf. Read the manual reference to it for a more detailed explanation.
For testing, you can leave all markets undeleted, and manually delete them when you are happy that the statement updated OK. Once you know the statement is working as you want it, you can automate market deletion.