Then I heard every creature in heaven and on earth and under the earth and on the sea, and all that is in them, saying: “To him who sits on the throne and to the Lamb be praise and honor and glory and power, for ever and ever!” (Rev. 5:18.)
Is this verse evidence of UR?
How can it be when the chronology of the book places this before the opening of the seals, the four horesmen, the judgements, etc.
How could every creature be reconciled to God before, they’re reconciled to God?
I’d say it definitely is, but I don’t know how to answer your last question, except to say the chronology of Rev is generally confusing 
Yep, prophecy is extremely sporadic as a general rule and flips back and forth all the time in chronology. One need go no further than OT prophets. Their messianic prophecies were intricately interwoven with both current events and eschatological predictions.
Jason even has the people praising God on the sea of flame as being those rescued from the lake of fire, how’s that? 
Where does he have that?
(Is it something I can read online?)
I think what you have here is John being given a snap shot of the end, of all creation worshipping in unity; then the book unfolds how we get there.
Tom
Some understand Revelation to be a series of similar Revelations from different perspectives, different facets of one diamond. Thus it is not Chronological and not meant to be understood that way.
Thank you.