I think there may be some confusion with the concept of regnal names here. During his life, it was correct to refer to the Shōwa emperor by his personal name, Hirohito. Japanese era names are chosen upon the emperor's accession to the throne, like European regnal names, but unlike regnal names, they are only to be used to refer to the emperor after that emperor's reign ends, as u/keyilan explains in this answer. That post is, in fact, a little out of date, as I'm sure u/keyilan will want to come say themself if I don't point it out: since the resignation of the previous emperor, Akihito, in 2019, he should be referred to as the Heisei emperor, and the current emperor is Naruhito, who will become the Reiwa emperor upon his own death (or abdication!). But that's another point — even though emperors are still referred to by their personal names until the end of their reign, their era names are common knowledge before that point, and are used to reckon dates since the emperor's accession. For example, 1945 was the year Shōwa 20.

I don't mean to knock your question, though — I think there's definitely an interesting answer to be written about how western media portrayed the Shōwa emperor during the war, but I am not qualified to write it and my reddit search skills are failing me a little at the moment.