Playing natural methods, the uninterupted auctions proceeds:
1♠ : 2♣
3♠ : 3NT
4♠ : 5♥*
5♠ : pass
*After an agreed pause for thought, east exclaims "oh dear - I thought you bid 4NT".
11 tricks made.
EW are quite inexperienced. Stayman and Blackwood represent the full extent of sophistication in their methods and they most definately have never heard of cue bidding.
So I guess the question is, does the UI that east thought he was responding to blackwood suggest that west bid 5♠ in favour other logical alternatives?