Originally posted by Greenneck Cc requested: color, blending, general astro stuff, focus.
What processing software did you use? That might help us to make applicable suggestions.
Color looks good as-is. There are so many different ways to handle color. As an experiment, you can try to increase saturation for more color, which might then need color temperature adjustments to avoid it looking overprocessed.
What was your exposure length? The EXIF says 30 seconds, but your description says 6 seconds * 4 exposures = 24 seconds?
Did you merge 4 exposures just to reduce noise, or did you do anything to align the sky? The latter allows larger stacks, but takes much more processing work when you have foreground in the scene.
Focus looks pretty good. Upper-right and upper-left corners look a little soft. Your 16-50 seems similar to mine - usable but not ideal for astrophotography. Corners are not great at 16mm and wide apertures. It's not a lens defect, the lens designer prioritized other characteristics.
Trees look sharp so I assume you didn't use the astrotracer. If you want to get into layering, take one long shot with the tracer for the sky, then a second non-astrotraced shot for the foreground.