No need to apologize.
It's definitely not your fault that GOG seems to allow (or allowed? I've not written any reviews here, so I'm unaware of any change to it) users to write reviews without actually having purchased the game from GOG itself, which would have prevented reviews like Tunareth's and the others reviewing the CD-ROM release from taking prominence over the product GOG is actually selling to its users.
Apparently, at least for Tunareth, if GOG didn't list the level editor as an included goodie then it was enough to assume that it wasn't included despite not having purchased the game through GOG to do something completely out of the ordinary and just check for themselves and potentially refund the game if it wasn't up to what they were expecting to find included.