Recording

These three work even when Junior is not the front window, so you can start and stop without leaving your meeting.

ShortcutAction
⌘⇧RStart recording
⌘⇧PPause or resume
⌘⇧SStop recording
⌘⇧MToggle your microphone
⌘⇧AToggle system audio

Moving around

ShortcutAction
⌘KSearch: projects, calls and actions
⌘1Home
⌘3Saved Calls
⌘,Settings
⌘OImport a file
⌘NNew project, when you are on a project
⌘JAsk Junior about the call

⌘3 and ⌘, are unavailable while a recording is running.

In the transcript

ShortcutAction
⌘ZUndo a speaker rename
⇧⌘ZRedo it

Questions

One of the recording shortcuts does nothing.

Another app has claimed it. Screen-recording tools and meeting apps are the usual culprits, and whichever registered it first wins. Free it up there, or use the tray icon and the sidebar instead.

Are there shortcuts for playing a call back?

No. Playback is mouse-only at the moment: no play/pause key, no skip. Clicking a word in the transcript to jump the audio there is usually faster anyway.

Why are some shortcuts blocked while recording?

Because they navigate away from the recording, and doing that mid-call caused more mistakes than it saved time. Pause and Finish still work.