I'm all for a better warning system or a message popping into the inbox indicating that the currency is filled. Or, better yet, I'm of the belief that attenuators shouldn't be capped. Though I imagine they were capped because they'll play a part in the next mod tier if it ever happens and they didn't want a stockpile if/when that happens.
However, I was merely pointing out where the OP was wrong in his assertion that a cap wasn't shown and explaining that I thought the current locations were consistent across currencies.
Similarly, OP says it was a busy 2 weeks, which is fine. Assuming they have Jabba, that's roughly 2x smuggler's run II events, so 120 attenuators. But the remaining ~180 attenuators to cap would be roughly Math.Ceil(180/0.19) * 16 / 645 ~~ 24 days worth of farming nothing but 9D mod battles using 3x refreshes and collecting all free energy. They could drop it down to ~15 days with 3x 50 cost refreshes, 3x 100 cost refreshes, and getting some free from the webstore, but if you're spending 6 refreshes daily on mods, you should probably be working on them.
0.19 used for the attenuator drop rate on the 16 energy node. My testing over 2,266 sims on that node gave a rate of 0.188, so I added a little extra.