Got this running recently and I tip my hat to you for it Zombie. I have a suggestion, for the asteroidTemplate and dustCloudTemplate checks, the tool should load up the mod's AsteroidDef.asteroidDef and DustCloudsDef.renderingDef files rather than using some default values. As, if someone uses any custom templates, the error checker can return hundreds of false positives, as it does whenever I run it, which is extremely annoying.
Ya, I see what you mean. I hadn't had any comments about this prior so didn't think about people modding those files. You could unzip the jar file and modify the planet.xml to in the meantime.
<field name="asteroidTemplate" validation="Any"></field>
And do the same for dust cloud templates.
Then zip it back up with the jar extension as before.
I need to see how much effort would be involved pre-processing those templates and adding them to validation.