It could save the buffer to the session file (if there is still one), and restore the buffer with a terminated command. That only use PC-based storage. So you'd at least not lose the "output-to-date" if winbox disconnects and windows are being restored. Now this still may not be possible since the "sessions" can apply to multiple hosts, so perhaps ONLY if profile <own> would this even be possible.
It's the "runs in background" if disconnected part that I do not support. Even if I "liked it", I don't think it is practical: both from a UX and technical POVs. e.g. winbox connection is what own the terminal: so no winbox, no terminal... & also given how winbox seemingly works, see Open-Source Python Reimplementation of WinBox Terminal Access)