I used some plastic to dIy a piece to fill in that gap, because I agree, it looks silly with the gap.
I had my velossa tech risers since 2017, been through snow and shine, no problems yet so far.
I didn't use any loctite, but I do make a habit of checking on the bolts every 6 months. It's not loose by any means, but I do notice I can give each bolt another 1/4 of a turn again, just for peace of mind.