If you read the instructions for 8938, it says:
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Duplicative Reporting
You do not have to report any asset on Form 8938 if you report it on one or more of the following forms that you timely file with the IRS for the same tax year.
Form 3520, Annual Return To Report Transactions With Foreign Trusts and Receipt of Certain Foreign Gifts (in the case of a specified person who is a beneficiary of a foreign trust, see Part III of Form 3520 and its instructions).
Form 5471, Information Return of U.S. Persons With Respect to Certain Foreign Corporations.
Form 8621, Information Return by a Shareholder of a Passive Foreign Investment Company or Qualified Electing Fund.
Form 8865, Return of U.S. Persons With Respect to Certain Foreign Partnerships.
Instead, you must identify on Form 8938 the form(s) on which you report the specified foreign financial asset and how many of these forms you file. See Part IV. Excepted Specified Foreign Financial Assets, later.
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Their use of the word "must" suggests that it is NOT an option to just duplicate the information from the 3520 on the 8938 and not report that you've also filed a 3520.
