We use P2 on a daily basis here and I NEVER import directly from the card any more: any time I did, trouble weas sure to follow.
I copy the entire card to a folder in my RAID drive first, then eject the card, THEN ingest into FCPX, and I don't get the problem you're seeing. I have a co-worker who is too bullheaded to take my advice, and he DOES see the same problem as you... wonders why none of the clips are in chrono order. I ask him: well, did you click in the list to MAKE them organize in chronological order?
"No", he says. And refuses to try. And he ingests off the card, which sometimes hangs. So I leave him to his devices.
It's a "best practice" I learned from Sean. You have a choice when setting up, to keep source files in place wherever they were, or to copy them into the project. Suppose you choose to economize on drive space and tell FCPX to leave files where they are... If you pull from the P2 cards directly, you create an association between the files on those cards and the project file. The project will always want to see those files coming from the same place, i.e. the card in the reader. Then someone comes along and pulls the card to go shoot something else; you can "break" your project and lose the file associations, and you got ketchup all over your file browser and timeline.
Also, your RAID likely has better performance handling those files than the card does. What time you lose offloading it first, you likely gain back later in peppier performance when actually editing. We use thunderbolt P2 readers from Sonnet and they are easily twice as fast as the Panasonic units. And three times cheaper.
So being a belt-and-suspenders kind of guy, if the footage is costly or impossible to replace, I always immediately dub the entire card structure into the RAID and offload a clone to cloud storage as well. If it's particularly one of those: this could make or end your career" things, as soon as I have it ingested, I'll throw it all down raw on the timeline and render out a safety copy in prores 422, before I start the actual edit.
But that's just me. I usually have a Plan B, C AND D. Based on painful experience.