You can enhance the spellchecking results of translate5s (which come from the integrated languageTool) by using ngrams for your languageTool installation.
For example with activated ngrams the "their" in the sentence "I can't remember how to go their." would be marked as an error. Without not.
Be careful: You will need an SSD hard drive to get high perfomance results.
For translate5 instances hosted by MittagQI the usage of ngrams for languageTool is standard from today on.
Ngrams are available for the languages Dutch, English, French, German and Spanish. Since LanguageTool is Open Source, you could contribute to make ngrams available for other languages or enhance the results for the existing languages.
Of course languageTool supports many more languages, but the ngram enhancements are only available for those 5 so far.