With the removal of mkvmerge's verbose identification output, processing data with line-based tools such as grep or awk isn't as straight-forward as it was before. You can easily process its JSON output with any language, of course, as JSON parsers are available for pretty much all of them.
For those that want to keep working on the command line, the jq utility offers a suitable replacement for those utilities. Here are a couple of tips & examples of what you can do by processing mkvmerge's JSON output with it. You can find out more about how its syntax in its manual.
I'm splitting up the arguments to the jq command into multiple lines for improved legibility. You should join them into a single line before executing them.
Outputting one line per track including the its ID, language and codec