For whatever reason, you are
not having knowledge or information about a situation, subject, etc
Just because you don't understand, doesn't mean it is necessarily solely your fault. It could be a combination of factors which make the situation, in your estimation,
Not expressed clearly: The host's directions to the beach house were unclear, so many guests got lost on the way.
Confused or doubtful; not certain: Our discussion left me unclear as to what you wanted me to do.
Therefore, you could say "I apologize for appearing uninformed, but it is unclear why X is being done Y way. If I could make a suggestion to do Z instead..."