8. "This is the main phase in the game, where a majority of a player’s cards and abilities are played. A player may choose to do any of the following on their turn:" "game, where a majority" should be "game, when the majority". "on their turn" should probably be "during the Combat Phase of their turn".
8.1.1.2 "only that type of card declared" should be followed by the "(E, F, or R)" clarifying text. 8.1.1.2.1 has it, but it really should be in 8.1.1.2 as well. This rule could probably use a cross-reference to the sections that describes "Form Card," "Enhance Card," and "Response Card."
8.1.2 "referred to as Resource Restriction." Should this be "referred to as the Resource Restriction" ?
8.1.3.4 "A player may also commit their character card like it was a foundation to make up the difference between the check and the difficulty needed." This sentence is unnecessary due to the change two sentences previous ("may commit a number of ready character or foundation cards"). However, this may be a good time to remind or cross-reference that multiple character cards in a staging area commit as one card.
8.1.3.5 I believe this should be split up into two separate rules. The first would be, "8.1.3.5 If the player fails an attempt to play a card, the card goes to the discard pile with no effect." The second would be, "8.1.3.6 If the player fails an attempt to play a card as a form, play proceeds to the End Phase (See 9.0 The End Phase)." That way it's clear that failed cards are discarded, whether played as form or not. The "from his hand" is unnecessary, because the results are the same whenever a player attempts to play a card, even if it's from the deck or discard pile (due to a card effect).
8.1.3.5 is followed by an extra carriage return.
8.1.4.1 "it will resolve as much of itself as it can." That's a lot of pronouns. It might be clearer to say, "players will resolve as much of that effect as possible." It's kind of awkward to talk about a card or an effect resolving itself, no?
8.1.5 "If you successfully play a character card, foundation, or asset, the card will have no effect while it is in the card pool." I wouldn't mind a slight hedging here along the lines of "(unless a card effect states otherwise)."
8.1.7.1 Was this always explicitly in the rules? Regardless, it's a good addition, since it's something that might trip up those who've only ever played Magic.
8.1.8 Has been necessary for a long time. Really good addition. It's a big change, too, right? Jaguar Revolver no longer fluctuates wildly. The only part that trips me up here is the last clause: "until another ability modifies that number." I think I get what you mean, but I think it could be said more clearly as a new sentence. Perhaps, "Other abilities may further modify the overall value (e.g., if the value was Speed, Speed may still be increased), but the base value of X becomes static when it is initially announced."
8.1.9 Is another great addition/clarification. Love it.
8.2 For clarity, this should probably say, "Activating a Form (F) ability"
8.2.1 For clarity, this should probably say, "Activating a Form (F) ability" and "playing a Form ability." (There are several cards on which "playing a form" refers to playing a card or an F ability.)
8.2.3 Again, "Form ability" would be more clear.
Or are we trying to move away from the old "form" terminology entirely? If so, many cards (Lien***, Order & Law, etc.) would have to be errata'd, and the first paragraph of the "The Combat Phase" section in the Starter Rules 12 would also need to be changed.