This is a continuation of my previous post.
Regarding the tires on the Ixia 125,
it seems "the front wheel has the tread pattern in the reverse direction" is the manufacturer's specification.
This information came from a fellow mechanic who handles Mavic products.
I also received about 3 comments saying "my 125 also has the front tire in reverse."

This change started with the tires on the Ixia 125,
so apparently the direction of the earlier Ixion tires isn't relevant as a reference.

I thought "but having the tread pattern in reverse direction doesn't make sense,"
so I independently installed the tire in the direction that prioritizes proper tread orientation.
Thanks for the comments and tips.