Short power = 寸劲 Fa jin done with little or no wind up. The ability to hit powerfully when the hand is already touching or at least very close to touching.
Wang Zongyue according to his classical "On Taiji", we see another way to look at the distinction of IMA and EMA that is not based on taoist vs. Buddhist or working your body inward or outward.
If you are referring to "Taiji Lun"/太极论 then I'd like to know where you feel he draws any distinction at all. Just skimming through it, I can find no reference to "internal" and "external" martial arts at all. He just discusses Taijiquan directly and without comparison to other so-called "external" arts.
He does make reference to "other arts" but does not classify them as "external" as you can see in the following passage:
斯技旁门甚多,虽势有区别,概不外乎壮欺弱,慢让快耳。有力打无力, 手慢让手快,是皆先天自然之能,非关学力而有为也。察四两拨千斤之句,显非力胜;观耄耋御众之形,快何能为。
Roughly,
There are many other styles [of martial arts], and although they are widely varied, they all rely on strength defeating weakness, the slow giving way to the fast, the powerful attacking the weak and slow hands lose to fast hands. This is the original nature of all things. This is not skillful and studied. The phrase "use two ounces to deflect one thousand pounds" means to win without force. When you look at people as they age, they lose their speed.
Where in all of that do you see a comparison between external and internal? Where do you even see a reference to "internal" at all? I think the quoted passage above sort of alludes to part of the concept but that's about it. AFAIK, Wang Zongyue did not make that classification. He only compared Taijiquan to "not taijiquan".