Questions about translating TCG rules

  • メインフェイスでは、手札にあるスキルカードを使ったり、自分のスタンバイゾーンにある行動可能状態の部隊が持つ「アクション」を好きな順番で好きなだけ行うことができます。

Hmmm yeah I wouldn’t trust my previous wording because of the typo (and I think I didn’t mean to use “then”).
I think in that case your interpretation is about right. Maybe the way it squares with the action phase is that it’s basically just saying that even the units that don’t end up being involved in a skill card - you still get to do something with those, it’s just that it can be a skill card or a regular action if they’re still active by this phase?

Oh, I agree with Notebooked, I think 処理 for something like an outstanding action would be processing that action in the sense that it DOES go through.

  • ゲームの第1ターンのドローフェイズからカードを引くことができます。

I think your description makes sense for this one. If you can’t normally draw on the draw phase of the first turn of the game, then this modifying that fits to me.

  • 自分の場にあるキャラカードが「使用部隊」となっているスキルカードを使い

This part also confuses me, but my best interpretation matches yours, i.e. that it’s when you use a skill card, such that a character card on your field becomes its 「使用部隊」.
What confuses me is となっているスキルカード sounds like the skill card itself is becoming the 「使用部隊」, but it’s possible the interaction with the が just before clarifies that (or makes it ambigious) and the modification of skill card isn’t directly modifying it into the subject but more like an actor involved (like the causer in causative form or that kind of thing).
I haven’t found any direct evidence confirming that (and I’d be curious to see it if someone does have it) but a skill card becoming 「使用部隊」doesn’t make sense to me from what I can tell of the game, so I think the best guess still stands (barring typos anyway).

  • プレイヤーやカードを撰び能力や効果は、自分と自分の両隣のプライヤーとそれらの場にあるカードに対してのみ行えます。

This one I’m also not sure about for the same reason as you.
If it’s definitely pictured as two sides across from each other facing each other, I could buy 両隣 just meaning your partner (on whichever side)
But on the other hand I could buy the description you describe of you + partner + person across from you, since games generally you sorta picture as being around a table.
Maybe the deciding factor would be if the possible effects are the kind of stuff where it would make sense to do them against either an enemy or a friend? Like if there’s one that could be played in there like “pick a player and destroy a unit” I think the you + partner + person across from you wins out.