English is a language with pretty reduced inflection mechanisms and overloaded word meanings. Translated into Russian you would be forced to use different builds for different meanings: “St. trinian’s is a pretty (in female gender, nominative case) school for little (in female gender, genitive case) girls” or “St. Trinian’s is a school for pretty little (both female gender, genitive case) girls”.
It's true that languages with case declensions (beyond the vestigial declined pronoun forms in English) would be less ambiguous in expressing that example sentence.
English is an analytic language, meaning that more information is conveyed through syntactic patterning involving closed classes of words like particles, prepositions, and articles. These words could be considered "overloaded" as you said, but for non-closed classes of words though, as far as I know English is not known to be more or less polysemic than other languages.
