I have a concern for a family member. Just trying to help
Based on the very basic research I did, taking NSAIDs (nonsteroidal anti-inflammatory drugs) with Cymbalta is contraindicated as they can increase the risk of G.I. bleeds. However, although Celebrex is an anti-inflammatory, it is in a different class than NSAIDs, specifically developed to be easier on the stomach. I appreciate your concern for your relative, as I'm sure they do, but it appears that this is a fairly safe combination (keep in mind that I'm neither a doctor nor pharmacist).
Of course, deciding to take any medication involves an assessment of the risks - there are always risks to taking medication - and should your relative wanting more information, they can discuss this in more detail with their doctor and pharmacist.