About language ability, I do not know the level of proficiency of the cabin crew, and it is a French Airline so despite views of English as a global language, I rather think EXPECTING the cabin crew to have good English is a bit unfair.
Having said that, I am also a senior IELTS and ESOL examiner and would say that IELTS 5 is not very high ability, especially when a 5 can come from a reading and listening score of 6 and a speaking and writing of 4 (overall band is the mean of the 4 sub-skills). Actually language testing is much more complex than anyone would guess, and any score needs interpretation and understanding. Frankly, being a language tester has made me not trust the validity (not to mention the reliability) of any measure of language ability.
TME