Your report seems to be in two parts as you put it yourself, firstly for "an unfair warning for something that's allowed in the server" and secondly "not having knowledge of what happened exactly."
Lets throw part 2 out the window, you cannot report someone for having a lack of knowledge, especially when action only came after you admitted guilt and after an effort was made to question you and ascertain the correct information. This is quite a silly add-on to your report and the dedication of two paragraphs to this element is unnecessary.
Part the second, "giving me an unfair warning for something that's allowed in the server".
The idea that nading a bunch of cops, including a paramedic, is allowed on the server when there was no activity and no attempt to chase you is inherently incorrect. The claim that nobody tried to chase you is backed up by a combination of chat logs which show cops talking to eachother in localchat while you threw your nade, and eye witness testimony. You can absolutely make the case that you thought the SR was still going on, but you were wrong. The fact you were wrong and the SR was not active, makes this something that is not allowed on the server. You being incorrect on the SR being there does not make Crash wrong. You're simply saying there was no malice in your actions, which we have no reason to disbelieve.
This being said, the facts as they are, you threw a nade at a bunch of cops & paramedic(s) after an SR had ended. This is simply deathmatching and is not allowed. A warning is a very fair punishment for this, as Crash obviously did not think you did it intentionally but he also felt it necessary to make it apparent to be more careful - this is the very essence of a valid warning.
Unless you can provide any evidence that the SR was still ongoing when you started deathmatching, the warning would stand as valid - and therefore your report would be invalid.
With that in mind, no further action will be taken. We appreciate you taking the time to report this issue, should you need to query it any further please feel free to reach out to myself or System on discord.