Would placing Voluma slightly higher in my cheeks cause any problems?

You're asking a very specific question about  the risks and benefits of various rejuvenation options.  I commend you for asking such a knowledgeable question.  I would strongly suggest that you consult with a highly experienced injector who understands both your aesthetic goals as well as the anatomy of the midface and the risks of each of your treatment options.  You can then make an informed decision as to how you would like to proceed.

Voluma (Juvederm Voluma XC) is a great hyaluronic acid based
filler that can augment and rejuvenate the facial appearance. A voluma natural
result not only depends on the location where the injection is placed
(…anterio-lateral, etc.), but also on the skills and experience of the injector.
Voluma acts as a “liquid implant”, therefore, injectors with great knowledge of
the facial anatomy like plastic surgeons or craniofacial surgeons should be
able to deliver a great natural looking results. Patients interested in facial
augmentation with voluma should discuss this treatment option with a Board
Certified Plastic Surgeon specialized in cosmetic surgery of the face.