If it is possible, that’s where I am thinking using the clip of 3PO that could deliver a line to ease Jannah and crew, so when Rey reveals why they need to go to the DSII.

If there was NO follow up with Jannah and crew and their motivation, then yes, it may seem strange they would help them. But later, we have the Jannah and Finn scene that they were storm troopers who left. So that in itself gives us a bit of explanation why they did not gun them down or anything, but decided to help. Even if this new portrayal of them are not actively helping the “good guys” (No more of the “We got a transmission from some random guy that you are the last hope, we wanna help!”) and they are kinda portrayed as like Finn’s moment on TFA (Finn was willing to help a bit in TFA, but not enough to go up against the FO at Maz’ Castle) … However, they wouldn’t act against anyone who is NOT on the FO side and especially those who are working against them. Why would they help the FO and gun such ones down? Wouldn’t make sense.

That is why fortunately, we have that scene between Finn and Jannah. That gives us some rational reasoning.

So maybe, it makes me think even if it “breaks the tension/shortens it” it would be good if C3PO, who has no problem blurting stuff out (even reprogrammed) something like “We are on a mission to save the galaxy” or something on those lines. Doesn’t have to be specific, but maybe something that he reveals they are the “good guys” and that prompts Rey to explain what they are doing. That’s the gamble now, double down on what side they are when Poe was not ready to reveal it.

EDIT: Is there less tension? Sure. But does it give us a more “at the moment” rationale why Jannah is willing to help? Yes. Even if it seems strange she would outright help them, does the movie later give us more explanation on Jannah and the crew, on why they would possibly have helped them then and later? Yes.