Magento has a different data model for customer. It’s more like a ‘contact’ centric system then an ‘account’ centric system. It treats all customer as an individual instead of a company.
If you are integrating Magento with Salesforce, perhaps you should consider the Person Account feature. It would be the good fit for the design.
If you really have to get the company information from Magento customer, you can get it from the address object. One Magento customer can have more than one addresses. Designing how the data synchronised between two different data set is crucial.
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