Generally speaking an architect designs buildings. Buildings firstly have purpose while providing for function. Next, from my understanding next is the environment the building will be built within. At task is the client or the owner of the building with a purpose and the buildings environment including the immediate neighborhood. That would have to be defined and may reside itself within a range of parameters - the immediate, the surrounding, the regional, and possibly further.
How culture enters the picture may be centralized with the purpose as to whether firstly if it is a public enterprise and its funding sources or if a private enterprise and its funding sources. Those sources are the power that will cause the structure to become reality. Those must be addressed by the architect designing the building. At task with the affect of culture just may not be architectural process itself since of essence it is only a tool or a machine providing for the inspiration causing an illusion to become functionality as reality.
Culture too may change the originality of a structures intent. A log cabin designed for a fur trapper to sleep, eat, and provide protection from the elements could very easily culturally become a school room for a community, a meeting place for regional land owners, or a place of worship for a few or many. Or, culture determines purpose for an existing building as an entity.