Having an official branch of the Communist Party inside a company stems from the days when they were a workers' party and needed to keep contact with the base. Huawei being unable to explain the formal decision-making powers of those representatives is unsurprising, considering that there are almost no formal rules to the arrangement. What matters is the informal function as a go-between. If the company wants government assistance for a project, they know who to ask. If the government wants the company to do something for them, they know whom to tell about it.
And yes, that applies to any company incorporated under Chinese law, even subsidiaries of Western companies (say Microsoft Research Asia, or Google China). How much power those representatives have depends on whether the company is willing to listen to them or not.
And yes, that applies to any company incorporated under Chinese law, even subsidiaries of Western companies (say Microsoft Research Asia, or Google China). How much power those representatives have depends on whether the company is willing to listen to them or not.