Indeed, I would remove “Moonlight” as this nickname has been added after the death of Beethoven, and is controversial due to its romantic nature, which was not Beethoven original intention.
However it is important to keep it in the aliases as it is the name under which it is known.
I would use as canonical name:
Sonata quasi una Fantasia (Piano Sonata no. 14 in do diesis minore), op. 27 no. 2
Reasons are:
- even though Beethoven was German, the work was published with an Italian title, as Italian was the language of music at that time
- having the number of the sonata in the Piano sonata collection is useful as there is no generally used “catalogue raisonné” of Beethoven work. Putting this in the name between parenthesis is from my point of view a stronger version of disambiguation notice.
From a practical point of view, we have to abridge the original names of most baroque or classical works. The naming style of that time lead to names which are way too long, as it often included in a long sentence, descriptive information, dedication, name of the author.
The actual original title of “Moonshine” is:
Sonata quasi una Fantasia per il Clavicembalo o Piano=forte composta e dedicata alla Damigella Contessa Giulietta Guicciardi da Luigi van Beethoven Opera 27 No. 2. In Vienna presso Gio. Cappi Sulla Piazza di St. Michele No. 5
“Sonata quasi una Fantasia” is capitalized, and in larger print that the remaining of the title, and therefore can be considered as the main part of this original title.
The current name should be an alias, as it is not in the original language, and it includes a nickname which is a romantic attribution to this classical work.
There are many other situation where the name most commonly used is not the name under which the entity is recorded. Chopin is recorded as “Fryderyk Chopin”, and not as “Frédéric Chopin” which is the name under which most of his work has been published, and has been his given name and his legal name, once he got the French nationality.