In many locales by law businesses are required to maintain certain sets of documents at their registered address. For example in the UK this includes at least the company articles of incorporation, although the list is more extensive than that. It's one reason many small businesses have their accountant as their registered address.

    Private limited companies must keep some or all of their statutory records
    at their registered office, unless they are stored at a SAIL address
    instead. These include the certificate of incorporation, the memorandum and
    articles of association and share certificates (if applicable).

    Furthermore, the following records and registers, where applicable, must be
    kept up-to-date and stored at the registered office or SAIL address for
    inspection purposes:

        Register of members.
        Register of company directors.
        Register of secretaries.
        Directors’ service contracts.
        Directors’ indemnities – security against liability claims or legal costs..
        Copies of resolutions.
        Minutes of meetings.
        Contracts relating to purchase of own shares.
        Documents relating to redemption or purchase of own shares out of capital by private company.
        Register of debenture holders.
        Instruments creating charges and register of charges

My presumption would be that the "raid" involved requesting their finance department furnish the inspectors with at the minimum whatever such documents are required to be held in France, and that such a "raid" would be standard practice at the onset of any tax investigation