Atarlost I looked into the symmetry issues you mentioned with the Tac Center. What I discovered from looking at both the 1x1 and 1x2 armor wedges is that the mirror mode isn't actually mirroring sprites at all. Walt has a predefined rotation matrix for the 1x1 wedge that simply rotates the part as appropriate when mirroring is on. The 1x2 wedge, which appears to be mirroring, is actually just using part substitution. When you place a 1x2 L in mirror mode, it substitutes a 1x2 R on the other side.
As there doesn't appear to be support for true mirroring at this time, it's not a change I can make. For the parts I have with asymmetrical door placement, like the Tac Center, I'm just going to leave them as-is. I consider it a design challenge in-game to make asymmetrical parts work with your ship layout. It encourages more interesting design. FWIW, there's no reason you'd need more than one Tac Center anyway, so the issue is somewhat moot.