Is there any tool/plugin for custom parsing jmte templates (mostly .json) in IntelliJ IDEA?

Question

In our project we are using JMTE(Java Minimal Template Engine) for templates (mostly in json). However, the problem is IDEA shows custom template parts as errors, and reformating breaks them. I was wondering whether there is a plugin/tool to add some custom rules for json files in IDEA. Here is the template brief example of template for better understanding:

  {
    "message": "${greetings}",
    ${if name}
    "name": "${name}",
    ${end}   
  }

I searched on marketplace, but could not find anything, as jmte is not so popular template engine. Also, I think, that creating our own plugin would work, but I just wanted to double check, whether there is some easier/existing way of making it work.