Sinking cherries

i was always taught to wash the sticky cherries then roll in the flour

I rinse the cherries in cold water and dry on kitchen paper. Always mix your fruit in before the wet ingredients.
Works for me ?

I think I'd be tempted to allow the fruit to drop to the bottom or even layer the bottom of the tin with cherries, and call it upside down cherry cake.

I am about to try a mango and coconut cake recipe. I shall dry the mango slices first, and roll them in flour.

Yes, wash and dry the cherries.

I just roll the cherries in flour and never had a problem.
Mix butter and sugar together, add beaten eggs , then flour and any fruit

I always put a bit of the cake mix in the tin - then add the cherries to the rest of the mix so that they've got 'somewhere to go' as it were.
I must add that firstly I wash the gunk off the cherries, then halve them again and again until they're in 'eights' as it makes them so much smaller and less likely to sink. They may look less spectacular but it's better than having a plain cake on top and all cherries below.

Put the flour, cherries and dried fruit in a tub with a secure lid. Shake thoroughly and coating is a by-lateral consequence. Cutting cherries in half can help. Sieve the flour out into the mix as normal, stir in the fruit last thing.

Tossing fruit – whether glacé cherries or sultanas, raisins, currants, dried cranberries and so in – in flour is fairly standard for ensuring that they don't sink to the bottom of your cake or pudding.

Have always kept an almost empty bag of flour just for this purpose. Only needs about a dessert spoonful of flour in the bottom. My 'go-to'cake is banana and cherry and I always wash off syrup, dry on kitchen towel then roughly chop the fruit. Thankfully read this tip years ago and followed it ever since.

Cherries are too heavy for your light mixture OP, even I suspect, when halved and rolled in flour.
Do as Lupin and others advise, and have a cherry upside down cake ? sounds delicious, I want some right now.