Is there a typo in the Russian transliteration table?

Problem/Motivation

Comparing #357254: Transliteration of Russian letters → to #2932249: Incorrect transliteration of some Russian Cyrillic characters → there is a change: "shch" became "sch". I suspect this is a typo: none of the tables on http://transliteration.ru/ uses "sch" and as I mentioned the contrib issue also uses "shch". ICU also uses shch here although that doesn't necessarily mean it's the desirable version, after all it uses "ts" for ц where our table uses "c" instead. ICAO also recommends "shch" in https://www.icao.int/publications/Documents/9303_p3_cons_en.pdf

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