Nothingness: Honestly, there would have to be some interestingly bad playing for that situation to arise, I imagine. But I suppose it could happen between people new to the game, or just kind of "randomly" playing.

I personally have never seen that happen. In my opinion, the way the rule is written here,

"One of the players still has some own pieces at his/her yard and made more than 30 (for 8x8 version) or 50 (for 10x10 version) moves. This player loses the game. The player also loses the game if he/she moves one of his/her pieces back to own yard after the 30th (50th) move. This rule prevents the players to block own yard and avoid the opponent to move his/her pieces there."

In looking around the internet a little bit, I get the impression that this is a "newer" rule, since sites like this came about. One place I read that normally, in face to face competition, moves aren't even counted. (Which makes sense)

As with many games, there are different philosophies too. Some rules state that once you are in the opposite yard, you can move within that yard, but can't move out of it. We CAN move out of it here. Another site I play at has a "forced" move rule, where if your opponent is completely out if his yard, and you still have pieces in your yard, you are forced to move out. (Regardless of move #)

I would think that temporarily going into the yard, in the middle of a series of jumps would be ok, but not ending there. I suppose the only way to know how it is HERE would be to try it, or ask Fencer how he programmed it. I don't think I've ever had a game get to that move #, so I've never seen it.