Surprising … in a good way 
My Capella is
Version: 1.4.2
Build id: 202010140908
I made the installation again, see the log in the end of the post
now it works, my template show the Capella and I am able to generate my Document 

The Log
Your original request has been modified.
“Apache POI” will be ignored because it is already installed.
“Acceleo Query SDK” will be ignored because it is already installed.
“Mylyn WikiText Twiki” will be ignored because it is already installed.
“Mylyn WikiText AsciiDoc” will be ignored because it is already installed.
“Mylyn WikiText Textile” will be ignored because it is already installed.
“Mylyn WikiText HTML” will be ignored because it is already installed.
“Jetty :: Utilities :: Ajax(JSON)” will be ignored because it is already installed.
“Mylyn WikiText TracWiki” will be ignored because it is already installed.
“Mylyn WikiText MediaWiki” will be ignored because it is already installed.
“M2Doc HTML Integration (experimental)” will be ignored because it is already installed.
“Jetty :: Security” will be ignored because it is already installed.
“Jetty :: Servlet Handling” is already installed, so an update will be performed instead.
“Feature for the M2doc Launcher” will be ignored because it is already installed.
“M2Doc UI” will be ignored because it is already installed.
“Acceleo Query Framework” will be ignored because it is already installed.
“Servlet API Bundle” will be ignored because it is already installed.
“Mylyn WikiText Confluence” will be ignored because it is already installed.
“M2Doc” will be ignored because it is already installed.
“Mylyn WikiText” will be ignored because it is already installed.
“Mylyn WikiText Markdown” will be ignored because it is already installed.
“Jetty :: Server Core” is already installed, so an update will be performed instead.
“M2Doc Sirius Integration” will be ignored because it is already installed.
“Jetty :: IO Utility” is already installed, so an update will be performed instead.
“Jetty :: Http Utility” is already installed, so an update will be performed instead.
“Jetty :: Utilities” is already installed, so an update will be performed instead.
“jsoup” will be ignored because it is already installed.
“Jetty :: Servlet Handling” cannot be fully uninstalled because other installed software requires it. The parts that are not required will be uninstalled.
“Jetty :: Server Core” cannot be fully uninstalled because other installed software requires it. The parts that are not required will be uninstalled.
“Jetty :: IO Utility” cannot be fully uninstalled because other installed software requires it. The parts that are not required will be uninstalled.
“Jetty :: Http Utility” cannot be fully uninstalled because other installed software requires it. The parts that are not required will be uninstalled.
“Jetty :: Utilities” cannot be fully uninstalled because other installed software requires it. The parts that are not required will be uninstalled.