No, you should not open a ticket because your forum posts got reported. People can report anything they feel breaks the forum Code of Conduct.
IF a Mod thinks it actually DOES break the rules, they will action the reported posts. If not, they can remove the flags, or just dismiss it.
You have no ability to see who is reporting posts. None. Only Blizzard can see that. If they see someone switching to alts to abuse the flagging and reporting system, they can (and do) penalize them.
This is not something they can help you with via ticket though. They won’t tell you who is flagging you. They won’t set some kind of “immune” flag on your account (there is none). They won’t talk to you about another person’s account.
If YOU see something that violates the rules, report it. If not, there is nothing more to be done. Just follow the rules yourself and let the Mods handle it.
Reminds me of this recent thread on GD which has now spiraled into almost 1000 posts.
Again, other players have the right to flag posts they think break the rules. The system will tell you if enough flag it to cause it to be temp greyed out until a Mod reviews it. Working as intended.