Hi,
I am posting this here as this may be useful to users wanting to install Acceleo 3 on Capella 1.3.
First, download this Acceleo version which is the one aligned with Capella 1.3 dependencies:
https://download.eclipse.org/acceleo/downloads/drops/3.7.4/R 201807201001/acceleo-update-3.7.4.zip
Use the zip instead of the update site as sometimes network issues/firewall/mirrors can make the update fail.
Then you should select the following to be installed (see attached image)
Then you should be good to go. Hope this helps!
Stephane LACRAMPE
ObeoSoft Canada