The parking at KSEA may need reviewed for accuracy (accuracy seems a goal of this sim). In some cases the same gate is listed twice. If these are A/Bs that should be indicated? The map I have does not indicate this, but my fading recollection of flying out of KSEA says they might be. There are also some missing gates that I think do exist like A3 and A6. I do understand there are some cases where gates x13 is properly missing in some concourses.
A gate level map for KSEA seems hard to come by. I used this