The information you are looking for is in the thread that you linked, first post.
To summarize, the version numbering works as follows:
<major>.<minor>.<bugfix> So when minor is one version behind, you are okay. When it’s two minor versions behind, you are in a form of suspension but you can be redeemed. Three minor versions behind and your node will be DQ’d.
So never be more than one minor version behind and you have nothing to worry about. I don’t know if Storj’s versioning policy allows for skipping minor version numbers (ie. v1.16.1 skips to v1.18.x), but you could probably take the current minor version number from
version.storj.io, subtract 1, and that is your allowed version. Your best bet might be to set yourself up a script that polls this value periodically (once per day would be fine) and notifies you when it changes. Or subscribe to the Engineer Discussions category, which is where changelogs are posted. Or subscribe to updates from Github.