Would it makes sense to reduce risk appetite on Stashaway by shifting funds from one portfolio to another lower risk portfolio on the back of bearish macro sentiments ?

Make sense. Maybe.
Wise to reduce. No. Go back to why you choose to invest in robo advisors. It is to dollar cost average and remove all emotions.
So 2 advices:
Stay rational
Stay calm

If u r still not convince, here's an example.
Your are an apple seller which costs $1. U intended to sell the customers at $1.20.
Because people has bad impression of your apple, u decided to sell at $0.10. And decided to sell orange instead for $2 because the locals like oranges. Will u do that?

There are only 2 things you should do.

Do Nothing Or top up more during this period.

If you are already thinking of withdrawing, that means you have selected too much risk in the first place. Using a robo advisor is meant to remove any emotional bias and panicking.

Stay invested and remain calm