If you are selling into a market not native to where you live, you absolutely should ensure the local language is used so you invoke feelings of trust and quality which will help boost your conversion rates. We are consistently adding new countries and our platform auto-translates for you so you don't need to speak their language to optimize for the new market.
Questions you could ask:
"After looking at this listing, do you see any grammatical errors- if so, where?"
"This product is popular in Germany, but we are planning to launch it in the US. What modifications would you like to see to make it more applicable or useful to you?"
"If you were choosing between these two brands, which would you prefer and why?"