This is your mistranslation. You need to interpret the two clauses separately.
a bound noun used to indicate that there are other things of the same kind as the thing that was just mentioned.
“등” is like “and et cetera; and so on,” in English, implying other more things of the same kind. “공격의 고삐를 늦추지 않았습니다.” is not what the “등” is implying.
When “등” is used with a clause (a verb), it works like a participle phrase (adverbial) in English: it translates to “Verb-ing … and so on,”.
“우크라이나 수도 키우프 제2 도시 하리코프에 집중 포격을 가하는 등,” translates to “Bombarding on Kiev and Kharkiv and so on,”.
“공격의 고삐를 늦추지 않았습니다.”
“고삐를 늦추다” (literally “to slacken/loosen the reins”) is an idiom that means “to lower the intensity,” by analogy with horse-riding. A horse stops running if you slacken the reins.
“고삐를 늦추지 않았습니다” is a negation of that: “not to lower the intensity; to increase the intensity.”
And with “공격의” (“of the attack”), it means “they did not lower the intensity of the attack,” which is the opposite of “alleviating.”