Welcome to the forum.
The torque converter vibration issue was due to the torque converter clutch trying to lock. It is independent of the engine RPM because it won't do it below 80km/h or above about 105km/h - it only vibrates in that range, and that's because it can't make its mind up whether to lock or not. It might be a tentative lock, or a lock-fail-release that causes the vibration.
If yours is vibrating in any gear at 2000-2100rpm then it's more likely to be engine-specific. Right at that point, your turbo is peaking and the full torque of the engine is being developed. Does the vibration change with different vehicle (not engine) speed? I'm trying to ask: is the vibration the same at 2,000rpm in 2nd gear as it is at 2,000rpm in 4th gear?
What kind of vibration is it? Is it a thumping, buzzing, ticking or rattling? Is this vibration isolated to the door and dash, or can it be felt by a passenger in their footwell, or the left-side A pillar? I am deliberately picking other areas to determine if the vibration is a loose dash and door, or a problem with the engine. We've heard of loose door strikers etc before.