We use CB's language translations for plan names. E.g. "Plan 1," translated for English, "プラン1," for Japanese- both translated from the plan name UE_PLAN_ONE.
I just tried renewing a members plan in the alternate language (Japanese) and was able to pay for the plan via PayPal, but upon returning to the site CB stopped me with the message:
"Payment notification mismatch: currency, item name or number or quantity mismatch."
Me thinks this is a bug: comparing the translated string instead of the plan id.