"How old are the ladies?" is not accepted. The suggested solution is "How old are the kids?"
When a Spanish noun has an -ito/ita ending, the English word "little" precedes that Spanish noun's translation. Thus, if you only goal was to communicate, then the translation you propose should be accepted. However, be aware that translating "señoritas" as "young ladies" is preferable, more literal. and hence better.
The popup says señoritas translates to young ladies, ladies or girls. Ladies is now accepted, but girls is not.
All the more reason for you to report it. When enough people do, it will be accepted by the program.
That statement is considered RUDE in the U.S. except when needed for alcohol, job or voting etc.
See. Here you translates "las señoritas" as "young ladies" which I used for translation for "Las señoritas tienen vestidos bonitos" and you wanted "young women". Very inconsistent.