Yes, afaik the transaction will still be on the blockchain only appearing when wallet online and fully synced but as you said i assume you do miss still some transactions. The beauty of RAIN being the rewards are random
Hope this helps
i bought some coins for check how much % stake they give,
but unfortunately my block size is just 2k , and 15 days, no reward
wallet is online 24/7 and fully synced.
should i buy more to increase weight of wallet to get reward?
In the debug console, type in "getstakinginfo" and verify both "enabled" and "staking" are shown as true. Also, there you can see "expectedtime" in epoch, by when you would get the stake rewards.