re the recent 7bm game.
There were actually two 'seed words' - nucleonic which was 'rare' and managed to muster 73 hits from a 'playership' of 351.
That was still more than the 'common' seed word (nucleoli) which had 52!
I got them both, but only because, having seen and played nuclei, I checked the COD to see if nucleic was also a word. That's when I spotted the other two, further down the page.
I think nuclei should remain common, although there has been a tendency to 'downgrade' Latin plurals, but the others?