According to an interview, she changed her name to the anglicised one at the beginning of her career and it seems the bulk of her appearances are as Evelyn Stewart, but I wanted a thread to make sure. According to Wikipedia, she also used the names Arianna and Arianna Galli, though seemingly each of these for only one film.

Evelyn Stewart
The Bloodstained Butterfly (Una farfalla con le ali insanguinate)
Syndicate Sadists (Il giustiziere sfida la città)
The Psychic (Sette note in nero) a.k.a. Seven Notes in Black
The Case of the Scorpion's Tail (La coda dello scorpione)
Footprints on the Moon (Le orme)
The Sweet Body of Deborah (Il dolce corpo di Deborah)

Evelyne Stewart
The Night Child (Il medaglione insanguinato)

Ida Galli
La dolce vita

Adios Gringo
Assassination
Battle Force
Cagliostro
Ciak Mull (Ciakmull - L'uomo della vendetta)
De Filippo - Fantasmi a Roma
Les derniers jours d'un empire: Collection Peplum (Il crollo di Roma)
Django Shoots First (Django spara per primo)
Fantômes à Rome (Fantasmi a Roma)
The Leopard A.K.A. El Gatopardo (Il gattopardo)
Hercules in the Haunted World
Rome Against Rome: War of the Zombies
Arizona Days
The Fighting Devil Dogs
Waterloo Bridge
hopalong Cassidy: volume 4
The Mexicali Kid

Quoting ninso4:

Quote:
There already is a common name thread
link

Thanks. It looks like her common name is Evelyn Stewart.