This is how I see Giulia's progress. She's only known one way to wrestle and that's the Joshi style, which is way different than the American style. To essentially be thrust from working Japanese style just a month before her debut, with no time to practice in the new style is not an easy adjustment. To be able to get fully comfortable in a completely new style in just under a few months is a daunting task. I have no doubt she can get there, much like IYO had to at the start of her WWE career.
With that said I feel like WWE has to stop treating her with kid gloves. I understand wanting to dial her back but it feels like it's hurting her.
Now Stephanie has been doing this way longer, a 16 year career compared to Giulia's 7 year career. Steph has way more experience in more aspects of the game so it's easy to see why she would shine more when it comes to adjusting to WWE's style.