These TCG rulings were issued by Upper Deck Entertainment and have since been deemed unofficial by Konami. They were previously considered official and can still be correct, as long as they follow the official gameplay rules, or unless Konami has issued a ruling that says otherwise. References: 
Fusion Monsters Special Summoned without "Polymerization" while "Fusion Gate" is on the field are still considered properly Summoned by a Fusion Summon. So they may be the target of "Monster Reborn", "Call of the Haunted", etc. (This does not apply to Fusion Monsters Special Summoned by the effects of other cards, such as "Magicial Scientist" or "Summoner of Illusions".)
Mentions in Other Rulings
Fusion Recovery: You can use "Fusion Recovery" to retrieve a Fusion Material Monster that was used with..."Fusion Gate"...
Non-Fusion Area: ...You can activate "Fusion Gate", but you cannot activate its effect [when this card is active because they are treated as Fusion Summons].
Sonic Jammer: While "Sonic Jammer"'s effect is applied, your opponent can still use the effects of...Field Spell Cards like "Fusion Gate".
↑Konami Judge Program Rulings are considered unverified, as their source(s) are not publicly viewable. They are not confirmed as applicable to the TCG until they have been officially published by Konami.