Hello,
I love Joplin and have it both on Debian and on Android cell phone. They sync and everything is good and shining.
I would like to use it as well on another computer running Archlinux, but I am worried that increasing the number of syncs may reduce reliability and introduce syncing errors.
Well more complex structures are often (not always) less reliable than simple ones.
I would like you to tell me that I'm wrong and that you tested it with ten computers and syncing is just the same, because the number of connections does not relate to reliability.
I sync via Dropbox to four devices, using iOS, iPadOS, Windows 10, Ubuntu (in Dualboot with the Windows installation). In past I also had another Windows device syncing and it worked great.
Even that "complex" structure of using a Dualboot machine worked without any problems. So from my perspective sync is super reliable in Joplin and one of the reason why I am using it.