I found that de-lidding Jubaeas, while providing incredibly fast germination, also provides incredible opportunities for mold to take over. Even after boiling water and pouring it over the soil to sterilize it first, I still lost every de-lidded Jubaea seed that I planted. They seem to be much more sensitive to mold compared to other seeds which I de-lidded (i.e. N. ritchiana), which germinated with few problems.
For Jubaeas, unless you've got a really sterile environment and can remember to keep it that way, I wouldn't recommend de-lidding them
However, you can still crack the outer shell. I cracked the outer shell of a few Jubaea seeds in the late summer, and am having pretty good results. When they were planted initially, I kept them outside in a sunny, hot area. I left them outdoors until temps reached around -7 C, then brought them indoors. Once indoors, they have been receiving no bottom heat and little water. Over the past month or so (so maybe 6 months after they were first planted), the Jubaeas have been germinating. I'm sure I could have sped up the process by a month or two by keeping them over high bottom heat. Still, 6 months is better than the year to germination which many people often report when leaving the outer shells intact! I also used the same temperature method for Butia eriospatha seeds, and am having decent results with those as well. I'll post some pictures when more seeds have germinated.