It worked! #EXWM #emacs, entering a standup report. Orgmode:
<f3> (start macro recording)
C-k (cut line, undo to put it back)
<C-x o> (other-window) to Firefox
Paste (yank, C-y), then TAB to go to the next field
<C-x o> (other-window) back to my orgmode file
next-line
<f4> to save the recording
<f4> repeatedly to do all this again.

I didn't expect it to work after the jump to a non-emacs place!