The order of the user-defined dictionaries cannot be changed.
The reason why this could be helpful: The order is reproduced in the "Add to Dictionary" right-click menu. If you have more than one dictionary (say one for abbreviations, one for names, one for everything else) it could facilitate the workflow to have the most frequently used dictionary right at hand, to wit: at the top. This feature would be espacially helpful when you add words using the keyboard (menu key > a) because the topmost entry is selected automatically.
Valid enhancement request -> set status to NEW
Best regards. JBF