their version of English is testing
Oh the irony of an Edinburgh based poster making that statement
Seriously, some Maltese do have a distinct accent (not all Maltese do and some speak with UK accents and have UK names, so be careful on the assumptions), but it is spoken as native English by many of the people, most being at least fluent (as Tom says) and after about a 30 second adjustment, you'll be fine.
By the way, English is an official language of Malta (the other one being Malti, which is not so easy to understand.)