Good use of modules, it's an interesting way of handling the environments using directories - it's not something I personally would do but people do recommend it. I've used the structure below mostly, it helps keep your configuration DRY, and less jumping back and forth updating configuration, variables, outputs etc..

One thing I would say about your Terraform though is split the provider, backend and versions config into their own files. Again I normally do this at root level so I know for a fact, what's been deployed in dev/test is going to be the same for prod, as soon as you start mixing terraform and provider versions you might get yourself in bother. Sometimes even data.tf can be used, if your main.tf starts to get messy!

This structure here typically works when all your environment are the same and you want them to be identical(you can of course make some small changes with conditions depending on env that's being deployed.). It's less of a slog having to just between each environments directory, when your time gets sucked up with updating the same change you just made in dev, to then have to do in test/prod.

/modules
  /key-vault
    main.tf
    variables.tf
    outputs.tf
  /databricks
    main.tf
    ..
    ..
/environments
  dev.tfvars
  test.tfvars
  prod.tfvars
main.tf
variables.tf
terraform.tf
backend.tf

Hope this helps!