The main problem I find is mixed language projects are not well supported like they are in Intellij. For example I'm working on projects using gradle and mixing Groovy and Java. In the past I was working on Scala/Java projects with sbt. None of these combinations are well supported by an LSP server. I think we need a polygot JVM LSP server that can support multiple languages and build tools seamlessly (just like IntelliJ can...).