UPDATE: 3 weeks have passed without any updates with the reasoning that its a third party investigation that they can not disclose.
Should I open up a case on one of those external websites ?
Sure, if you want to wait faster. That'll definitely help.
Your case is a third-party investigation related that's out of Rollbit's control. Creating a complaint on CasinoGuru, AskGamblers, or other "external websites" will subject you to the same waiting period and frequency of updates as you have right now.