What volume of data you are discussing? How many physical nodes? Can you give a complete usage example of what you want to achieve?
In general, there’s a steep change in making things distributed properly, and distributed systems are often designed for big and complex situations, so they “can afford” being big and complex too.
Running LanguageTool locally is a bit of a pain, with some manual steps. Plus you have to fetch some data files. You can find around a few projects like this one to make it easier to run LanguageTool.
And yes, as the poster mentioned, LanguageTool keeps some code exclusive to their paid version. There’s a bit of a tension because they ask people not to extend OSS LanguageTool with their paid features.
There’s also this interesting clone, but it seems abandoned.
I assume you basically want protection against disasters, but not high uptime.
(E.g. you likely can live with a week of unavailability if after a week you can recover the data.)
The key is about proper backups. For example, my Nextcloud server is running in a datacenter. Every night I replicate the data to a computer running at home. Every week I run a backup to a USB drive that I keep in a third location. Every month I run a backup to a USB drive on the computer I mentioned at home.
So I could lose two locations and still have my data.
There is much written about backup strategies, for example https://en.wikipedia.org/wiki/3-2-1_backup_rule … Just start with your configuration, think what can go wrong and what would happen, and add redundancy until you are OK with the risks.