FB Ads strategy - getting a consistent €0.06 CPC

I sell vintage-style wall decoration of old maps (https://www.vintagestadskaart.nl/ site is in Dutch).
FB advertising was difficult at first but my current strategy yields great results. I imported a spreadsheet, and every product has its own adset. In that way, I can target every product (200+ maps of different towns) to the respective locals only. Generating the spreadsheet was automated with a Python script.

CPC is very good (4 to 7 cents per click). As a comparison, no location targeting increases CPC 10-fold. However, location targeting is only possible at the ad sense level. I believe FB will not learn from audiences between ad sets. Does anyone have ideas to improve this further?