Full Idea
The title as given by the artist is something we might need to know (Brueghel's 'Icarus', for example), ...and if a painting depicts one of two twins, it will be the artist's intention that settles which one it is.
Gist of Idea
The title of a painting can be vital, and the artist decrees who the portrait represents
Source
Stephen Davies (The Philosophy of Art (2nd ed) [2016], 3.5)
A Reaction
Those two points strike me as conclusively in favour of the importance of an artist's perceived intentions.
Book Reference
Davies,Stephen: 'The Philosophy of Art (2nd ed)' [Wiley Blackwell 2016], p.67