I fear that the "Memory" achievements not counting is intended. But since the concern was forwarded, we'll hopefully get a definitive answer from Nexon.
Obviously all events will eventually move to memory once no longer active so if they don't intend to count the memory section then stop attributing points to event achievements in the first place so people stop wasting their time. It makes no sense to offer achievements for events only to erase that progress towards your score weeks later. Hopefully they fix this or at the very least announce that event achievements will not be permanent additions to our score so we can stop wasting our time.