The forum is just the “each one teach one”-part (one might simply replace teach by help…) whereas the devs depend on gitlab for their work.
You can just create your account: Report an issue and describe each issue in detail so the devs have some reliable source and someone to come back to for questions.
In general (not only in gitlab but also here in the forum) it is helpful to provide specifics about the installed software [HOWTO] Give complete /e/OS version info easily for support, answers, comparison etc.
Also the specific phone model should be named, especially as you seem to have issues with Dual SIM. I already assumed (see a few posts above) You are talking about 930FD (and I further assumed it might be a Dual-SIM-specific issue) but You never confirmed your S7-model so far.