In your original post you wrote that search string 'Fl' doesn't work for 'Fremish', but 'nl' does work for a value containing 'nl'.
This made sense because 'Fl' (consecutively) is not contained in 'Fremish'.
I assumed you'd intentionally misspelled Flemish as Fremish because you were hoping some fuzzy logic search functionality exists.
Additionally, l and r are a long way apart on the keyboard and so it did not seem your misspelling was sn accident.
Thus, based on the information you provided, my reply was structured accordingly.
And the image you posted even showed 'nl' working.
But now you're saying it doesn't?