Hi Max,
Congratulations on your designs, they are playful and would fit right into a Muji catalog.
However obviously being high end, I don’t think Etsy is the right platform to sell these on.
I bet you will have more success with a dedicated website, shopify integration and intense Facebook marketing campaigns.
As far as the Plus signs go, they determine your design and often people desire a more modern, flush type of look for their interiors to keep things calm and clean. To avoid associations (Kermit eyes, dead eyes etc.) it is good to stick by a philosophy. In Europe, people often live by ‘calmness, cleanliness, regularity and discipline’ and we want our interiors to reflect these life principles. You would have to research the aesthetic preferences of your market a bit showing them alternatives, and also offering alternatives (materials, colors, details, premium add-ons) in your web store to show that you understand your audience. That is when people will connect and as a result, purchase.
Also retargeting strategies are important especially in markets where people do not buy on first contact, but need some time to decide.
I think these are wonderful and if you approach your marketing well, you will sell.