Currently Supervision Server script is the only option to restrict the range of the values entered to cubes. Could you consider to add a new feature that enables users to restrict the range of the values entered to cubes without creating their own Supervision Server script.
On excel we can force the user to put only number for example or only number between two number. Or only date, only a precise format and specific rule. It could be great (at least) to force the user to put number in cell. But in fact the best you can do is have the same feature as Excel and put one more feature concerning REGEX. It could be very great if we could force the user to enter a well writted email without format error. With regex we could check if it respect or not the good syntax for an email or something even more complex.