Generally one uses circa 585mm height cupboards if the ceiling slopes,
sounds like someone has used circa 720mm or such like. Shallow depth
cupboards are required if you go much lower than 18" if you do not
have an "Ikea 0.72m football field depth worktop".

Anything above a hob has to comply with clearance requirements, which
would render a microwave unusable never mind unsafe (tip hot dish all
over yourself). Additionally they are not designed to be mounted over
a heat source, some in the USA are - but they are built into units
often with dedicated ventilation kits (and forced ventilation kits).

Likewise you need a certain clearance above toasters (heat) and
kettles (steam).

Quite a few people would like to see a cupboard-free area for
toasters, because a stuck toaster can cause heat damage or worse to
cupboards situated directly above.