After looking at the photos here
and on Oberon's website I was also concerned with the looseness of the bottom two corner straps, presumably because of compatibility with both the 505 and 700..
I emailed Oberon to ask if I could have a cover with these straps tightened to suit the 505. They emailed back to say that this was their design and they were satisfied that it was correct, (ie No).
I ordered my cover & when it arrived I was satisfied with the quality of the materials and that the workmanship was no better than to be expected from a 'craft' item.
I do agree with the OP however that the bottom two straps are far too loose, (the right hand one being loose enough to insert a wine bottle cork), in my mind making the reader vulnerable. At $26.00 postage each way I do not have the opportunity to return my cover for correction.
When I get the opportunity I will take the cover to a local leather worker to see if I can get it corrected.