> A 2016 study shows that, in terms of basic everyday language, speakers of Maltese are able to understand around a third of what is said to them in Tunisian Arabic, which is a Maghrebi Arabic related to Siculo-Arabic, whereas speakers of Tunisian Arabic are able to understand about 40% of what is said to them in Maltese. This reported level of asymmetric intelligibility is considerably lower than the mutual intelligibility found between other varieties of Arabic.
Arabic-origin words make up a minority of Maltese vocabulary, and I assume Maltese speakers are much more likely to watch English or Italian television than MSA, and most don't have Quranic education.
What would the rest of the vocabulary be based on?
AFAIK the most common words are more likely to be of Arabic origin, though.