Im not sure then, Im also on Win 10 now. But I've always had the cracked version. The only thing that stopped working for me when switching to Win 10 was the face preview part on the roster not working anymore.
I would suggest a trial and error approach. Try edditing the tri-nations file (27f224714b2839695c21a148b77fa99b) change the index numbers of the three teams to
Once you load up tri-nations (try both years/random) the teams to play with should be Saracens, Toulouse and the Hurrincaes.
If that does not change anything ingame, you might have to import all those files into your datagob file, as originaly, all files are being read from there. Just make a backup first.
I hope this helps.
I have tried other rugby games but keep coming back to this. Dont know how all the newer releases got so much wrong. The WL is a gem, I try to balance out the roster (lowest rating 30, highest 99) and replace half the team I would start of with players with a rating of 30 - 40. I also use the select one defender per phase "trick" and try to slow the ball from time to time. This makes it extra hard.