Hooray! Another Swarm loophole. The way Gate is written is that it is an un-targeted attack against all creatures. Therefore it hits all creatures, but I would say that the way the Swarm trait is written (RAW) it only does a maximum of one damage to them. I would love to be wrong about this.
Technically, there is no RAW for Swarms in Arena, so I guess it's up to Arena players to agree on rules for Academy for each of the new keywords and traits (e.g. Frost, Defrost, Swarm, Potion equipment, Breeches equipment).
First, the Academy rules are RAW for Arena. No need to spread misinformation.
Secondly, Gate to Hell, as Puddin pointed out, is an attack that is untyped. It has no symbol to determine the type of attack that it is (ranged, melee, or zone) so creatures with the swarm trait will recieve 1 damage as the G2H is not a zone attack.
I'm fine with your Gate to Hell interpretation, but I don't agree with your point about Academy rules as RAW for Arena. I agree with iNano on this point.
Do you have an official source as reference for your statement? This would help clarify several areas that currently are left to players to decide relative to differences in the rules. For example, if what you say is true, then the Pest trait in the 4th edition rulebook of Arena should be changed to the Academy version and included in the Codex and Rules Supplement.
I understand the position that AW has about Academy cards being compatible with Arena but to me this is different from saying all Academy rules are RAW for Arena. If that were the case, then we would need to remove the Planning Phase from Arena games to reflect Academy RAW.
A more concise integration of the product lines from a rules/supplement/card effects point of view would help all players and play testers.