However, you could try to convey the sentiment using phrases that capture the essence of a free spirit and a wanderer:
* ʻUhane huakaʻi (Spirit of travel/journey)
* ʻUhane kūʻokoʻa (Free spirit)
* ʻUhane holo (Wandering spirit)
* ʻUhane ʻāina ʻole (Spirit without land/boundaries)
You could also use a more descriptive phrase to capture the specific qualities you associate with a gypsy soul:
* ʻUhane me ka naʻau aloha (Spirit with a loving heart)
* ʻUhane me ka ʻuhane hoʻokalakupua (Spirit with a magical soul)
* ʻUhane me ke aloha i ka ʻāina (Spirit with love for the land)
Ultimately, the best way to translate "gypsy soul" in Hawaiian would be to choose a phrase that best fits the context and your intended meaning.