Hello. Kobotoolbox doesn’t have this function yet? substring-after (). In ODK have it and serves to convert Geotrace to KML.
No, KoboCollect does not support substring-after() yet. The relevant PR for javaRosa is here: https://github.com/opendatakit/javarosa/pull/393, which was pulled into ODK Collect v1.19. So either Kobo needs to rev KoboCollect to a recent version ODK Collect, or alternatively pull in just this PR. Either way its basically a new feature request for Kobo (@mike.destaubin?)