I can say it like this then.
I unlocked lost drm keys forever. I relocked my phone using flashtool. Drm keys still not there according to what we know.
But all the functions you mention works. I've compared pictures with ones that comes from a locked bl with never was unlocked. They are the same quality. The other functions you mention works aswell.
And remember now, I don't have any drm keys. But I have relocked bl. I unlocked last night again. And I actually checked these things just to see and guess what. They all still worked.
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OnePlus One Black Sandstone edition 64gb - Stock
Xperia Z1 - Stock kernel - .108 - Unlocked Bootloader - Rooted - Has it´s own life
Xperia V - New display and working like a charm.