The argument you introduced is something we often hear in Japan, too. But I don't know Russian, and I don't know how strongly Russian people dislike loanwords as compared to Japanese. That said, I think Japanese people are generally tolerant of loanwords.
Unsurprisingly, in samurai dramas and Japanese fairy tales, loanwords are normally not used. We hear 匙 instead of スプーン, 暦 instead of カレンダー, 厠 instead of トイレ, and so on. But this is probably not because loanwords are "soulless"...it's just that they were not used in those days. Haiku generally consist of native Japanese words, too, but I think using katakana words is no longer taboo in modern haiku. Of course it's perfectly fine to use スプーン if you want to write a sequel of Cinderella, for example.
Will using them frequently make you sound like a try-hard that wants to seem "advanced" but just ends up being really silly and awkward?
Yes, there is a word that buzzed recently and describes exactly this: 意識高い系 (lit. "highly conscious folks"). This is a negative-sounding stereotype of someone who tries to act like a "global businessperson" even though they are not capable. Trying to use difficult loanwords is one of the typical characteristics of 意識高い系 people.
To take an example, the following is a real help-wanted ad issued by Rakuten: 楽天の求人がルー語でヤバイ！
カナダのKoboチームと時折コミュニケーションを行い、グローバルなベストプラクティスを実践していただくグローバルなオポチュニティです。
Or see this "Greetings from the president" (although apparently this is an intentional joke): 意識高い系社長の挨拶文 カタカナ英語が多すぎて何を言っているかわからないと話題に
2000年初頭に起こったパラダイムシフトにより様々なキャズムが取り払われ、各社のコアコンピタンスがコモディティ化された結果、先の見えない不況が我々の眼前に覆いかぶさってきています。LIGは自社の強みでもあるファクトベースにおけるブルーオーシャン戦略、いわゆるボトルネックを排除したベネフィット創出事業にフルコミットする事で、安定的な成長を続けています。
A typical response from ordinary Japanese people would be something like "What the hell is this guy saying? He can't even speak in Japanese!" Well, note that these are a bit exaggerated examples. In reality, few people try to use katakana words intentionally because most of us understand that doing so won't make ourselves look intelligent.
Here's a list of words 意識高い系 people tend to use: 意識高い系が使っている用語が話題に…。
