what you re asking for is to set the “thousands separator”
see also those 2 topics:
EDIT:
there might be some workaround with using an additional line (a rhino object), and textfields with format
%<'{:0.3f}'.format(CurveLength("459884e9-fc3b-44ed-b7e2-7dcff614d019"))>%
But I did not find any approach that is supported by Rhino s textfields that allows to set " " as thousands separator.
EDIT 2:
further digging: … if it is really a must have, a custom script can set a static Text with the desired format - but this will kill the associative / dimension history. So this might be a pre-print step and then after printing / export going back to the last version with standard interactive dimension/annotations. a bit of a hassle