Here they come for 2019. For the little these require sets, i.e. only to find the common elements among two character arrays, I think that it would be pretty easy to reimplement them without, for earlier versions.
StrikeAMatch.vi
StringDigrams.vi
Regarding Levenshtein: Wladimir Levenshtein developed 1995 an algorithm for this. It is called the Levenshtein Distance.
Some years ago I developed a VI to calculate the Levenshtein Distance. Here it is (LabVIEW 2016).
Can you post your VIs in LV2020 or 2019, please.
Levenshtein Distance.vi
You can use the shortcut menu on a property node to select the .NET class. The one you are looking for is in the mscorlib assembly.
System.Environment.vi