Tumbling, is a specific action of the Acrobatics check.
As long as you do not have the encumbered or overburdened condition (see pages 275–276), you can use Acrobatics to move through a space threatened by an enemy or enemies without provoking attacks of opportunity from them. Tumbling is a move action, and you move at half speed.
Your movement from Trick Attack, is part of a Full Action, thus you cannot Tumble as part of it, as they are separate actions. The same as you cannot Tumble as part of the movement on the Charge full action.
the action economy pretty clearly shows this is a no go. Trick attack is a full action that includes a move so sadly as written the rules don't allow it. Ive actually let a operative do this in my game however because it just bothers me that they make a acrobatics, stealth or whatever check to justify the trick attack without any real in game RP reason to make the check. it seemed harmless enough, however seeing as there are exploits that allow a similar function I see doing this would make those superfluous so I may have to rethink that house rule. So far there is been no real downside or balance issues come up but now it bothers me that it makes that exploit less valuable.
The RP reason is using a skill to deceive and create an opening against an enemy, by feinting, surprising them, being just that quick or carefully reading them (i.e. bluff, stealth, acrobatics, sense motive). That opening gives you a chance to nail them where it hurts.
oh I understand the principle it just doesn't always apply as well to some of the skills involved and has always felt a bit clunky to me in practice but I get around it with fluff descriptions like you mentioned
