(Native Russian speaker here) I don’t really agree. The “t” and “ch” require very different tongue and jaw positions and combining them is awkward and would require a vowel in between when used in a real word.
English speakers are perfectly capable of pronouncing ch vs sh (e.g. chair vs share) whereas sh vs sh’ (ш/щ) might be more challenging.
Especially since there exist words in russian language that actually have "т" before "ч", and the sound it makes is different. Compare "отчёт" and "очки" (the closest similar word i could think of by the sound of the first half of it). If you try pronouncing the first word as if "т" wasn't there (or the second word, but as it "т" was there), it will sound both very different and wrong.
That (the IPA designations) could, and probably is, helpful for breaking down sounds on paper but taking that /t/ from what is a manual of sorts and dropping it into a foreign transliteration is the opposite of helpful.
Everybody expect the French won't have any problem reading out without stumbling Chkalov or Chmil. Supplying the /t/ is a copout to please the French and, as a bonus, to piss of the Russians (especially the Chekalovs ones).
English speakers are perfectly capable of pronouncing ch vs sh (e.g. chair vs share) whereas sh vs sh’ (ш/щ) might be more challenging.