yes- that is a very bad amount of honey to leak out- I have never seen so much. I would tell that friend to:
a) Make sure frames are fully capped before harvesting
b) Crack the frames in 1/5th increments- allowing 20+ minutes between cracks.
c) Only harvest one or two frames at once
d) Harvest when the weather is cooler if possible
If you do the above the leaking will be minimalised. By only harvesting one or two frames at a time- the bees will have a much better chance to clean up- move out of the way- and deal with the leaks.
personally I would also first clean the coreflute and then put it in the bottom slot- if it is in the top slot and that much honey leaked it would pool at the bottom of the hive and bees would drown in it.
It’s interesting you say ‘coastal’ my mothers hive is also coastal- and her honey tends to be thinner than mine- and she has had more visible leaks. However by following the above rules the last 3 times we have harvested that hive we have only seen very very small leaks- certainly nothing like in your photo.