Quick question

When the ijin clan oni with haste uses the haste token then moves 3 or more to a enemy model it gains ijins horns (+1 Attack)
and uses the haste token for a second attack does it get +1 attack for the horns

I don't have the book in front of me but I believe the wording for Ijin's horns says the ninja gets +1 attack if it moves 3 or more spaces. That's it. Once it moves that 3rd space, it's attack stat is +1 for that turn, regardless of the number of times it uses it's attack stat.

According to how its written seems that its legal to move back and forward before attacking so that ijins horns are activated.... Is this intended or should it be written in another way?
Maybe "if model with ijins horns attacks a model that is 4 or more spaces away before moving it gets +1atk"?

I see nothing wrong with doing the attack bonus shuffle. The bonus is mostly prevented (or made risky) if you put the horny ninja in and surround them with, other ninja influence zones.