1) is fine, you can use they to mean his words. You don't need to write his words in brackets as it is clear to the reader without it. 2) There wasn't A sufficient amount of snow on the track thereFORE ski competitions were postponed. (or better) There was INsufficient snow on the track thereFORE ski competitions were postponed. 3)They were apprehensive with regard to the measures that could be implementeD if they are caught. (in this sentence you have used two different tenses change were to are or vice versa to fix it EDIT: this actually works as it is in the right context, if they were apprehensive in the past about the present or future) 4)Quite a few people felt irritatED BY the song that became popular recently. (your original sentence isn't actually wrong but sounds weird) I just used capital to highlight

1) i the first sentence, replace they with it as "they" is only referred to living objects. 2)The second one is correct 🤗 3)The were apprehensive regarding the measures that could be implemented if they were caught ( or had been caught if you refer to past) 4) felt irritated (you need adverb not noun after "feel) 🥰 If you gave some more question, don't hesitate to contact md 😃

Coming from a native speaker, it is perfectly fine to say 'they' when you're talking about words in everyday language.

1) is fine, you can use they to mean his words. You don't need to write his words in brackets as it is clear to the reader without it. 2) There wasn't A sufficient amount of snow on the track thereFORE ski competitions were postponed. (or better) There was INsufficient snow on the track thereFORE ski competitions were postponed. 3)They were apprehensive with regard to the measures that could be implementeD if they are caught. (in this sentence you have used two different tenses change were to are or vice versa to fix it) 4)Quite a few people felt irritatED BY the song that became popular recently. (your original sentence isn't actually wrong but sounds weird) I just used capital to highlight

1) the pronoun "they" is used for people, so you can not use for "word", in this case you should use "it" referring to his words. 3)replace "are caught" for "were caught" since you're speaking about the past. 4) felt irritated.