Here are my thoughts:
1. I haven't brewed with this yeast (or any Kveik), but I have heard they are fast fermenters. So your overall timeframe to finish fermentation in ~3.5 days sounds legit. Yeast under pressure ferment somewhat slower, but if you're keeping it around 10 psi, it might not be too long.
2. With a lot of krausen, it can stick to the top of the Tilt, dry, and then mess up the angle it sits at, making the gravity readings less accurate for absolute value. So your actual gravity might be lower or higher than 1.006 its showing now. With you having two yeast blowouts in your spunding, you definitely check the box for "a lot of krausen". So I would be shocked if your current reading value is very accurate right now.
3. The chemical reaction of yeast converting sugar to alcohol makes CO2 as a byproduct. So if your spunding is off-gassing, your yeast are still working, adding CO2 into your headspace. So regardless of your Tilt reading, if you're still getting gas out of your spunding, just let things keep going.
4. The point of the spunding is to control the MAXIMUM pressure in your headspace. At start of fermentation, your headspace isn't all jammed up with CO2 molecules, so the pressure is low, and your spunding doesn't off-gas anything. As fermentation continues and more CO2 is made and goes into the headspace, it starts to get crowded and pressure starts to rise. Once the pressure gets to the level of your spunding, it starts operating like a bouncer at a night club- the amount of CO2 into the headspace matches the amount of CO2 released. If you want your headspace nightclub to hold more guests, you crank up the pressure setting. However, you will reach the mechanical limits of your fermentor at some point and you have to relieve some amount of pressure so it doesn't burst/split/balloon. Plus, there are limited studies out there on homebrew pressure fermentation, but they do seem to indicate 10-15 psi spunding is better than 28 psi. So you do want it to be constantly bleeding off CO2, in order to not over-pressurize things.