Normally, Ueno-chan learns more specifically how her attempt has failed. In this case, she's left completely misapprehending things. And, in this case, Tanaka is left thinking that she had intended something quite bad that she hadn't. So the chapter leaves me more unhappy than amused.
The “manoculars” coinage was quite good. The invention itself is more Ronco-esque than is typical of Ueno-chan; that is to say that the gloves are something like a Pocket Fisherman; many people would mistake them for practical.