I re-wrote the values in the tuning plugin to apply just intonation to selected sections of a score.
For each key there are two tunings:
... major /... minor, where the second is lower to make a pure second minor chord.
... minor /... major version, where the second is higher to make a pure major fifth chord.
There are many other chords available that you can play with.
I also attached the LibreOffice sheet where I calculated the values and from where I exported them to the plugin.