I've got Crusade, so I can't easily try out the base game.  In Crusade, the Space Elevator and Computer Code do get a flat level bonus.  So perhaps you've found a bug, or perhaps that item was meant for the Crusade section of the change log instead of the base game section.

Yeah, I just looked at the XML for both the base game and Crusade.

Here's the differences:

Base Game:

• Manufacturing Cost:  12
• Maintenance: 1
• All Production bonus: +1
• Per Level bonus:  +10% to All Production/level
• Adjacency:  +1 to All Production

Crusade:

• Manufacturing Cost: 20
• Maintenance: 1
• All Production bonus: +1
• Per Level bonus: +0.5 to All Production/level
• Adjacency: +1 to All Production

The Computer Core has similar variation: a slightly higher construction cost in Crusade, and a flat vs percentage bonus in Crusade/Base Game.

Can't tell if this is a documentation bug, or an intentional one, due to slightly different balance strategies between the two games. My *guess* is the latter, but that's just a guess.