If etsy tells you your titles are decreasing your search ability, do you trust it? They tell me my titles are too repetitive (aka having wall art/poster/print etc in there too many times) and that they should only be around 8-9 words long. What I'm doing is taking keywords that have really good rankings on Everbee (200+ monthly searches and under 15,000 competitors where possible) and using all the characters I can have in the title. Each keyword is separated by a | .
An example title:
Donkey Brushing Teeth | Bathroom Prints | Animal Bathroom Posters | Animal Posters | Donkey Prints | Funny Animal Bathroom Prints