If svn update worked reliably
Feel free to submit a bug report, since if the unreliability is a KoLmafia problem then it should be fixed.
I will note that several reports I have received about "not working" have been operator or scripter error. If the user chooses not to do updates on login then they will have to trigger updates manually. Script author "errors" have included not setting the repository up in the manner expected by KoLmafia, trying to manage updates from within the script and not using expected filename and directory structure conventions.
In the specific case of chit I note that the version of chit that KoLmafia will install from the Script Menu is Bale's version hosted at SourceForge and not the LASS fork at GitHub. It is a known bug that if both versions are installed the "wrong" version can overwrite the newer version. The KoLmafia Community has not really dealt with the technical and social issues around the Scripts Menu when there are forks or competing versions.
If the unreliability you note is caused by this known bug then it would certainly be worth a Feature Request and a discussion about the contents of svnrepo.json and how to deal with forks and renames.