Yes. In fact, formal engagements can result in K-1 being denied
Do you have a reference to this? Specifically that supports this:
I dare say the average visa journey experience is the opposite. I personally consider any ISO, CO, or CBP officer who demands wedding plans to be mentally defective.
As for: “photos of an engagement event”, including these can, not surprisingly, result in denial of the K-1 visa.
Engagement events should be as informal as possible, and can happen later or not at all. A quiet dinner between the couple is fine. A 1000 guest “engagement” event, is a denial.