I would recommend to contact Giuspen directly about you need.
Below are two alternatives:
Other possibility is to use shell alternative, I can share it with you:
sudo apt-get install meld
mkdir -p ~/.config/caja/scripts
cd ~/.config/caja/scripts
wget https://gist.githubusercontent.com/N0rbert/b0b11340e588b33fab542b0c72837e41/raw/6ec7f6ccea71ac3d473038c4ae66041494a24688/meld
chmod +x meld
it will be available in Caja when you have selected 2-3 files or 2-3 folders: File → Scripts → meld . See screenshots:
- single pane operation
- dual pane operation (F3, View → Extra Pane)
As temporary substitution you can try to configure custom action using Caja Actions Configuration Tool from caja-actions
package.