"Those" is the plural of "that" - I didn't spot it consciously until until I learnt my fourth language, Italian. We were learning Questo, Questi, Questa, Questae when I thought, We don't have plurals like that in English...then "duh" yes we do for one vs. many: this -> these, that -> those. Latin does it all with endings (like Italian!)
Where do you live? Never seen that in Europe, (where religion is a kind of taboo, and a private matter.) Isn't it too noisy in markets to pray?
I think we can imagine fake temples, like small temples for tourists, but in Asia, there are temples in market according to this: https://fr.tripadvisor.ca/LocationPhotoDirectLink-g1092107-i22251672-McLeod_Ganj_Dharamsala_Kangra_District_Himachal_Pradesh.html
Templum, -i is a neuter noun belonging to the second declension. The plural ending of the direct cases (nominative, accusative, vocative) of neuter nouns of the second declension is -a, resulting in "templa" in this case. The adjective "illa" is the nominative plural of the neuter adjective "illud". The paired adjective and noun must be in the same case and number, in this case nominative plural.