Dear Xara...

...I try and use all my applications and websites as both mouse-driven and keyboard-driven to better understand my end-users difficulties.
The XDAs have a very rich keyset of functions that I find enhances workflow and productivity.

Many XDA functions are hidden behind context menus and until now I have never thought of accessing them other than mouse right-click.

The Windows keyboard has an AppsKey, usually physically under the RightShift key and it appears to be used in all other windows applications as their Menu key to invoke context menus, all except the XDA.
You can even assign it as a customised key shortcut where it is listed as 'Application'.

Could you confirm that this is the case?

I am fortunate that I have a workaround as I can use the AutoHotKeys application.
My script is:
;============================== Program Xara Pro+ ==============================
#IfWinActive, ahk_class XTPMainFrame

AppsKey:: ;Menu key ==> Right Mouse
  Click Down Right
  KeyWait, AppsKey
  Click Up Right

It seems a serious omission that you ought to fix.