Timequest reports inverted SDRAM clock as shifted + 180 degrees

Looks good to me. I would also do a report_timing -hold on that path, just to make sure that is correct, as you should have a positive hold requirement.

I personally use derive_pll_clocks instead of explicitly constraining them. Yes you lose the ability to name the clock and instead get the ugly, long name, but I've seen enough projects get messed up because the .sdc didn't match the design, that it's my general recommendation, but it's really a matter of choice.

As for the -invert, you need to analyze yourself if TQ correctly picks that up. Feeding the actual registers, TQ can identify simple inversions, but when sending a clock out it gets more complicated. For example, I've sent a clock out using a DDR structure, where I tie the high register to ground and the low register to VCC. TQ doesn't recognize this as an inversion, and I have to add a -invert. It sounds like just a simple inversion won't be noticed on the clock line, so what you've done is correct.