My understanding was that the Saturn 10-player mode supported widescreen and, in fact, encouraged it so that all players could see what was going on. Regular battle mode is 4:3 but 10-player supports wide.
It doesn't matter how many players there are, you get to choose "Wide" arena in the pre match options. There's only one wide stage, but you select it before the match as if there were others. It may not send out a 16:9 flag or whatever, but its proportioned to be viewed on a widescreen TV, so its the same difference.
It looks like the Saturn builds the map from the regular tiles and sprites and just scales everything down. I'm guessing that it was a late addition to the game. The space for the extra resized graphics wouldn't have been an issue.
Wait, I don't recall hearing about Namida being for the PCE, only the PC-FX, that's wierd..
It started out as a Super CD, then became an Arcade CD, then got moved to PC-FX where screenshots revealed new/different characters, then years later development resumed for Gamecube and PS2, until finally it was released only for PS2.
I hope the Gamecube version gets ported to Wii.