in general practice, the use of parentheses for cautionary accidentals is reserved for rare and special cases.
for example, I'd use it if a large chord in the piano, widely separated, had a C# at the very bottom, but a C natural at the very top... the parentheses in this case indicate that "no, this accidental is NOT an error".
however, an arpeggio with a C# near the bottom and a C natural somewhere on the way up would NOT have parentheses as the notes are not simultaneous. simple cautionary accidentals (or in this case, just "accidentals") would be enough.
otherwise, they should be reserved for special editions for editorial markings.