FelicityR, on 2020-April-14, 01:21, said:
From my experience I would say yes. Only alert if asked. As far as I understand - please correct me if I'm wrong other commentators - most bids over 3NT are not alertable. And whilst your partner cannot see your explanation and the opponents can, the bid is still (I presume) highlighted in yellow in the online bidding box. So, whilst not telling your partner the actual meaning of the bid, your partner would have some notion that it is conventional in some way.
Bids above 3nt should be alerted in the first bidding round. For example 1
♠ - 4x being a splinter must be alerted, 1
♠ - 3
♠ - 4x being a cue bid not. But it could be that are different rule for different zones.