Note that starting from DataMiner 10.0.9 feature release and 10.1.0 main release, with the introduction of RN26251, large values are already displayed with a thousands separator to improve readability. It uses the thin space character (\u2009), not a comma or period as to avoid confusion with different localization cultures.

One the one hand this improved readability may be enough, on the other hand this will probably break the RegexReplace proposed by Jarno, but a more accurate one can be composed to replace the \u2009 character with a comma.