I’m noticing the upper levels have more words with strange translations and missing meanings.
西暦 is the latest one. The only accepted meanings are “Christian Era” and “Western Calendar” which are both correct, but the Japanese Wikipedia page and other online dictionaries like Jisho also use CE, Common Era, Anno Domini, and AD as accepted translations. As best as I can tell, all of the accepted meanings for 紀元前 should be also be allowed for 西暦. The Wikipedia page for 西暦 even links to the English page Common Era.