It seems, you are using the mirror function of elog. It should resolve conflicts by itself acording to the documented rules. (https://elog.psi.ch/elog/config.html)
As I don't use this function, I can't say how good it works.
If you don't want to use this function, I would suggest using the "Execute new | edit | delete" feature to trigger a script after each change of elog entries.
This script could itself run "rsync" or your sync solution to make the sync and
should afterwards call "killall -HUP elogd" on the remote to let elog re-read the config (and this sould also update the indices)
(see Server Configuration https://elog.psi.ch/elog/adminguide.html)
If you have a sync-solution, which itself permanently observes folders for changes and syncs it by itself,
It should have the option to run a command after sucessful sync or you need an other method to call "killall -HUP elogd" after sync.
Personally I would recommend the mirror function as it has a internal conflict resolution.
I hope this helps.
PS: I don't know anything about your setup, but maybe there is a solution, where you don't need the local servers.
As I think, the mirror function is mainly for backup reasons of a main server to a secondary one or similar.
We have a number of local ELOG servers, all mirrored to a single "remote" ELOG server. We have users that create updates at the local server, and some at the remote server, which can run the risk of record conflicts. Right now, the local servers perform a "Mirror cron" every 5 minutes, but even that leaves the door open to potential conflicts.
I found an open-source JAVA-based app called DirSync Pro (https://www.dirsyncpro.org/) which is capable of performing real-time mirroring, and has conflict handling. I "took it for a spin", and it does do what it claims. However, because each ELOG server performs record "indexing", it doesn't recognize records that aren't part of the current list of records. Restarting the ELOG server obviously corrects that, but I was wondering if there is another way to get the server to recognize newer "remotely-generated" records without restarting the server.
As always, I'm appreciative for the outstanding working that has been done to make ELOG the great application that it is!