Learn English – Is it correct to say “don’t let it trouble you”

1, It's not correct in regular English

2, It might be correct in Western Scotland - don't argue with people who think The Wickerman is a documentary.

3, Your wife is always right - that's the point of wives.

'Kindly' = 'please' in this usage; it's a hedging pragmatic marker.

However,

'Please/kindly let us know whether you agree with the suggested approach'

comes across as an instruction or even an order.

'Would you kindly let us know whether [or not] you agree with the suggested approach'

(still not needing a question mark) contains sufficient hedging for all but the most cantankerous.