In the commit template from Mylyn (Preferences > Mylyn > Team), the number of accessible variables is very limited.
It could be usefull to access any field value in a tracker with a dedicated variable, taking the field name as an argument.
E.g. using "${tuleap.field("reference")}" to access the value of the field named "reference" in the tracker.
This is technically made possible by bug
https://bugs.eclipse.org/bugs/show_bug.cgi?id=415013 which allows arguments in template variables, though it is not explicit to the end user when using the autocompletion right now.
Hence, the documentation of such a "tuleap.field" template variable should be explicit to indicate the end user how to add the field name as an attribute.
The name "tuleap.field" is naturally not definitive and I am opened to better suggestions.
The variable could also take additional arguments for formatting (for example the date format) or for simple value-label mapping when working on a enumerated field.
I am currently working on an implementation using the "org.eclipse.mylyn.team.ui.commitTemplates" extension point and the tuleap connector. If that's OK with the team, I could contribute that in a separate plugin (due to the additional dependencies to org.eclipse.mulyn.team.ui and dependencies to other eclipse or tueleap tasks plugins).