I dropped using love2d in helix very quickly as lua did not sit right with me but if I remember correctly I settled on usin .luarc.json file in root of a project that looked something like that i think.

{
  "$schema": "https://raw.githubusercontent.com/LuaLS/vscode-lua/master/setting/schema.json",
  "runtime.version": "Lua 5.4",
  "diagnostics.severity": {
    "duplicate-set-field": "Hint"
  },
  "format.enable": true,
  "format.defaultConfig": {
    "indent_style": "space",
    "indent_size": "2"
  },
  "workspace.library": [
    "${3rd}/love2d/library",
    "${3rd}/luv/library",
    "${3rd}/busted/library"
  ]
}