Three general categories missing:

1. The core stack of internal (or internally created but also external) - protobuf, gcl, etc

2. Some more well-known languages that aren't as big in Google, but are still used and people wrote indexers for: C#, lisp, Haskell, etc.

3. All the random domain specific langs that people built and then worte indexers for.

There's a bunch more that don't have indexers too.