(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.
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.