Hi,
Yes you are right! As per my knowledge it is not possible to restrict. I think you need to update the Group key with right justified or leading zeros.
for example see the below screen shot. I think you can educate the users to update the group key with leading zeros. (ex: 000014520,
00001452)
My opinion: either you can use the equal values instead of range or change field updaes with leading zeros.
Thanks,
Kiran