If I may...
I agree with the proposal to substitute "artificial" with "constructed", but I'd like to point out that terminology in this field is not fully standardized. For example, some authors use the term "constructed language" only for languages created for artistic or private purposes. Besides, languages tend to handle the issue differently. In German, for example, international auxiliary languages are generally called "Plansprachen". Most authors, including myself, treat "constructed language" and "artificial language" as synonyms.
Also, the common belief that there is some kind of binary dichotomy between natural and constructed languages is misplaced. Ultimately, every language is, to some degree, the result of deliberate human intervention. In other words, every language can be placed somewhere on a scale of artificiality, and it is not like a thick red line can be drawn between both extremes. As a matter of fact, some languages usually considered natural (especially reinvented languages and certain standardization proposals) can as easily be considered constructed; some of them even have a single author and a year of creation. Modern Hebrew is a good example of a language that really belongs to the grey area of languages that are neither fully natural nor fully artificial.
Best regards, Jan van Steenbergen