Is "increased echogenicity" a standard radiology term for fatty liver, or would it mean that the echogenicity increased since the first ultrasound?

Ultrasound: The degree of echogenicity depends upon the ability of the tissue being evaluated to reflect or absorb the ultrasound waves. A fatty liver will attenuate (weaken) the ultrasound beam somewhat, decreasing echogenicity and limiting full evaluation of the solid liver tissue. The terminology on your report probably refers to the echogenicity of a specific area relative to surrounding areas of tissue.

Increased above nl: Phrase means increased above normal. Comparison to other studies would br stated as such.

Compared to normal: "increased echogenicity" typically means that it is increased compared to the standard liver echogenicity. If it was a comparison to a prior ultrasound, that would likely be stated more explicitly. Increased echogenicity does not always mean the liver is fatty - there are other potential causes - but fatty liver is the most common cause.