Very French! Reminds me of Follis tandem forks, main diff being the Follis lower plate had tabs extending forward and backward to a fender mounting hole.

And this design has proven plenty strong for tandems, even loaded for touring. So probably fine for MTBs, short of extreme air




The French also usually angled the lower plate to follow the angle of the tire as it passes under, angle due to the fork offset. Mostly for fenders, not usually found on MTBs