Thank you @ Cambrian @ houthakker @chrillek
The good news today is the specialists helped me with the script:
Actually it was a pre-existent one, already in the treasure box of devontechnologies
Name
Add Returns in RTF.scrpt
tell application id "DNtp"
try
tell text of think window 1
set n to (count of paragraphs)
repeat with i from 1 to n
make new paragraph with data (return) at (after paragraph (2 * i - 1))
end repeat
end tell
end try
end tell
Now with a keyboard shortcut set up in macOS System Preferences, when there is a text, which lost its paragraph returns, one shortcut will do, mine is ALT CMD P.
So this is solved = SOLUTION!