Don't let players use the exact same word multiple times!!! Just because they add an 's' or another noun doesn't mean it should be accepted!
You are correct and adding an ‘s’ should not count it as a separate word. If you could send support a ticket with the word/category we can remove the word from the database and it will then only accept the singular version of the word.
Adding other nouns after the first word has been decided to be permitted in the mobile version.
David Justin Welker Junior commented
Before best because I'm able choice friends who I want play with also show pictures to identify. How many people that I want play from one to one, one to two, or one three or all player of four. But Today, I can choose friends but requires four while I have three people to play not fourth. Not able let us three even two. All keep fourth with different automatic player that I not want. No pictures identified. What happened????