I have to disagree. At its most general, the concept of efficiency means "desired output achieved per unit of scarce good expended" and can be applied in a variety of contexts: new users per dollar spent on marketing is a measure of your marketing efficiency, treasure value found per hour spent searching is a measure of your treasure-finding efficiency, etc.
Heat pumps are just a case where a) we use the same units for output and input even though they're different things, and b) in that unit system, the value for the output can be greater than the input. Since people can be unnecessarily suspicious of >100% efficiency, they use different terms for it.
If you expressed the efficiency as "2 joules of heat moved per joule of mains electricity consumed" you eliminate the canceling that would let you phrase the ratio as 200%.