Hello and welcome to the forum!
Yes it is possible, anything is possible, and changing player names certainly is. The main problem you will have is fitting the real names into the tiny spaces allocated for them in Japanese.
For example, looking at the Ireland team and their player オルゴリッジ (Orugorijji, which I can only assume must be [John] Aldridge), you have 6 characters for that, and that appears to be the most you can fit. Of course, Aldridge is 8 characters, so it won't fit.
Unless you can do some assembly hacking, you're not going to fit more than 6 characters in each name slot, and there are going to be many more players with longer names than Aldridge.
So, in summary, it IS possible, but you'll either have to a) make concessions by cutting off the end of players' names, or b) do some serious hacking.
That's my view, anyway.
ps. I examined the file in Tile Molester and couldn't find the Japanese font anywhere. Lots of graphics for players etc but I couldn't spot any fonts. Not sure how I'm missing it.