Typically, "at expected level" means between 8 and 12 scaled score--25th to 75th %ile.
The attention results could be good--or not. Generally, the Dx of ADHD would not hinge on a single test score. Presumably, there were other data sources (behavioral rating scales, observations, maybe a computerized assessment, like the CCPT or TOVA). Also, individuals can use cognition to compensate for a certain amount of other EF deficit. It may be that the relevant difference is actually that inhibition is "only" at expected level, while all other cognitive and EF skills were above. Keeping in mind that the two core deficits in ADHD are believed to be in regulation of attention and inhibition/impulse control.
