Best method of asking for street / flat number for an international address

I'm struggling to think of an appropriate label for a specific field in an address form fieldset. We have a service that is used by both local and international customers that asks for their home address - we have an additional complication that sits on top of this;

The address is sent via API to our partner service so that our customer can complete their task. This API service requires a specific format, or the task will fail. We require the first form field of the address to include a number - if there is no number present, the task will fail. This is a government service, so unfortunately we have to play by their rules here.

Our current label is "Flat, suite, unit, building, floor, etc." - this was spotted on Amazon and trialled, but we find people are writing things like "House" in this field. We need to cater for a very wide variety of addresses from many different countries.

There are some subtle differences depending on country of residence selected. For Hong Kong and Singapore (two of our larger customer areas) we don't show "City", and for Hong Kong we don't show "Postcode" either - so we are OK with showing conditional fields.

I am preparing to suggest a new label, being "Street number" with an additional hint text that reads A flat number, building number or house number can also be used

I would love to hear any suggestions people may have.