You successfully changed the word "WARN" to "DEBUG". Very nice. We discussed this offline, but just to keep a record: as long as a warning is displayed elsewhere when a WCS fails and this passes tests on Jenkins, this ticket is good to merge.
I do think that at some point this issue should be revisited, in that the reason these log messages are SPAM is because makeWcs is being called even when it is known that there is no WCS information in the image. A better solution in the future might be to only call makeWcs (and other similar methods) when a WCS is both needed and known to be present.