The IDE experience looks awesome, congrats on that.
It looks like the language decision is made. But I’m curious (and a bit surprised). Why couldn’t you do those IDE changes with YAML? It looks like the new LookML language represents the same data structures as YAML (and then the additional meaning comes from a layer above those structures). If YAML’s liberal syntax was a problem for users / your compiler, there are other standard alternatives to creating your own language.
For us, this seems to be a step away from what we love about Looker - a flat, explicit way of modeling and representing our data with the minimum of interference. A new proprietary language adds to that interference.