I'd echo parthy's reply for Kirsty as well. Apart from one mistake which possibly Emma could also have made (as well as those that have gone), she's done well. Stepped up when she's seen the need to and correctly read most situations.
I think the short run of six episodes is unfair to them. Unlike the Apprentice proper, most of them have very little practical experience of working for real. So they haven't the variety of skills including people skills that would stop them making silly mistakes. Which is what the program makers are hoping for.
Kirsty apparently works in her parents' restaurant. You'd think front of house so will have some customer experience, which showed Ep1. With the artist she failed to recognise that he was a customer with a choice and not a supplier or wholesaler. But she'd never been in that situation before.
Arjun has had the advantage of being teamed with Zoe. Plenty of opportunity to roll eyes and dialogue with the most talkative candidate.