16 is probably way too low for min res, I wouldn’t go below 64. I would expect 64 min with a 512 lightmap to produce the same results. The minimum resolution is basically a balancing act, you want it to be as low as you can get it while still getting good results, but you don’t want it to be too low or you’ll be wasting too much of your texture space on padding.
Your remaining artifacts I’m guessing are probably related to how you laid out your UVs, I’m guessing you did not create a UV seam on the edges that are still showing lines, and so you’re getting bleed from neighboring texels.
It’s hard to understand your UV layout but I assume you need to break these off into their own UV islands:
