Yes, all building names are used in plural in the game.
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This is working as designed. I chose to use only one string for each building type to simplify both the translation side and the development side. This is in line with the guidelines on BGA Studio:
The BGA translation policy is to be flexible on grammar... We prefer to write "player gets 1 coin(s)" than write two versions of the same string for plural and singular - it reduces the number of strings to translate.
Yes, there are situations where all the building names are used in plural. In addition to the example mentioned by N_Faker, the win condition string says something like "Early victory! Sheila has built all temples and towers." Sentences about zero/none would also use the plural form. The end-of-game statistics also use the plural form "Huts destroyed", "Towers placed", etc. (and in that case, the platform doesn't give us an opportunity to have separate singular/plural strings)
In English you could write "hut(s)" but that doesn't work for all words in English (foot/feet), let alone all languages.
Basically, is "Sheila places 1 hut(s)" really different from "Sheila places 1 huts"? For me, no. These sentences are both equally wrong but still clear. To properly fix this, we'd need separate strings for "hut" and "huts" ... or maybe even more strings like "a hut", "${count} huts", etc. since that numeral 1 is awkward, too. We're not doing that.
I updated the translations for these three strings only ("huts", "temples", "towers") to have "(s)". I think it's absolutely no better than with the regular "s", but if it will shut everyone up, fine.