Sorry but I just get lost among all the text here.
Master folder means do not accept any changes from anyone.
Each file and directory is version, and each device advertises the version of the file it has. By default, master folder means that the version will stay the same, always as it does not accept updates (unless modified by the master node itself).
Now if someone in the cluster modifies a file, the global version (which all nodes see) gets incremented, causing the master to become out of sync, and causing all non-master nodes to download the newly modified file from the modifier.
Override changes tells the master to take the global version of all files, increment it by one, and advertise it to everyone, causing everyone in the cluster to download all the files the master has (as this is now the newest version).
SHA3 will only give you part of the answer. We track permissions, mtimes, internal flag changes (which might not be readable by you externally) part of the version, hence you are getting only part of the answer.
Versioning settings have explanations to them as you select them.
These are meant for versioning as it’s explained, which involves archiving files before modifying them.