Why is the term "Ki" still not used in the English dub?

[xzero]

In the first episode featuring the Xingese characters, the FMA: Brotherhood dub used "ki".

So apparently Funimation has no problem with "ki" as long as it's not in DBZ.

This is totally post hoc reasoning, but in DB/Z/GT, the characters all talk about Ki and energy in normal parlance. For something so common, it makes sense to use words an American audience (not strictly an otaku audience) would understand whether they were viewers from the beginning or not.

By contrast, when the Xingese characters show up in FMA: Brotherhood, it's sort of a one time thing as I don't recall any subsequent mentions of ki in the series. Even if there were, however, it's still different because as compared to Ed and Al, Lin is a foreigner with foreign concepts, ki being one of them, so it's more "proper" in a sense for him to mention and describe ki to the uninitiated Ed and Al.

[KaiserNeko]

In the first episode featuring the Xingese characters, the FMA: Brotherhood dub used "ki".

So apparently Funimation has no problem with "ki" as long as it's not in DBZ.

Let's not ignore that DragonBall Z had been dubbed WITHOUT the use of Ki in it's entirety before FUNimation started dubbing Brotherhood. It had never been used once in all the years they'd been dubbing it besides the video games. So, it's no surprise they never tried shoving it in later down the line.

[Piccolo Daimao]

Perhaps "power level" is more marketable to the HARDCORE power level-obsessed fans, rather than the more spiritual-sounding "ki".