The inlet coolant temperature is limited to 60 degrees C, which is assumed due to the close approximation to power electronics circuit. Is it a particular problem if the inlet coolant temperature rises above 60 degrees C?

It would be possible, but it depends on how efficiently you are operate the radiator. For example, for the FCM50 higher inlet temperatures would lead to derating of the full power output. Many applications don’t need max. power all the time, since most load profiles show dynamic power demands. Derating will be only applied if the max. power output is requested for several minutes.