Crypts, in my experience, are unpredictable! Sometimes it seems like a crypt melts for no reason or sometimes you can uproot it and it's fine.
Here's what I would do - I would remove the leaves on the beckettii and lucens that have algae on them. If not removed, these leaves may melt anyway due to lack of light that can get to them, if they are covered in algae that bad. If you are careful not to disburb the roots while you trim, they should not melt. Are all 12 old leaves on the lucens covered in algae? If the lucens in a group is working for you and you like the look, then leave them that way. If you want to separate them, it may make them grow a little faster.
I had a lucens growing up through a narrow-leaf sag. It grew so fast through the sag and didn't seem to mind all the sag leaves around it. When I did separate them, because the crypt was becoming invisible in the sag, the lucens melted two leaves (still had about 5) but then a new leaf appeared in about two weeks. If you do uproot some crypts, trim the roots a little and be sure to put a root tab under them. This seems to help so the melt won't be as bad. Before I moved my lucens, it went for 6 months without a melt.
I had two beckettii once. They did grow slowly, but they got to about 6 inches tall. Their leaves were held a bit more upright than a wendtii. After I moved the beckettii, they never recovered. I eventually threw the tubers out because they never did grow any more leaves and and the tuber was very mushy at that point.
For your Anubias nana, I would also trim off any old leaves with algae. One of my nanas had six leaves and four were covered with algae. I trimmed the four off and I was worried that I would kill it. Within a few weeks, it had four new little tiny leaves! I have read that trimming the algae-covered leaves will usually stimulate some new ones to grow. In my experience, that seems to be true. Even if the leaves aren't too algae-covered (but ususally older leaves do have some algae), trim off the older ones to get some new leaves to grow.