例句中既past perfect tense, 求解

標準的文法書對past perfect tense當然會以相對past tense的時間次序作前後句 (你所說的conjunction句子)，但是除此之不是這種寫作時也會出現不是比對式的past perfect tense。我相信你引用的WTO和Balano的tense是因為是一段report新聞報告或經濟報導等，所以要全都用past tense。而這些所形容的事件實際上作都想用perfect tense來表達它們是剛發生的事件，但由於全篇都用past tense，所以每每寫到原意為present perfect tense的事時，便改為past perfect tense。

我讀這些句時腦中意思是：

由於世貿協議，中國已經撤銷對外國零售商...的限制 - 報告過去式。
Balano的對手已經在主要地點進駐...-報告過去式。
Balano已經遇到嚴重的員工短缺，他們流失... - 報告過去式。
或者把「報告過去式」印在頂頭才開始讀這文章。把當中的所有過去式讀成非過去式。

這只是我的讀文方法。不是說這種寫法或文法無用，它是有其作用，只是中文上沒有這種時式時我的變通看法。

All these three statements are in "Reported speech". When the tense in the original statement is in present perfect tense, it has to be changed to past perfect tense.
Report speech in general
Original tense ---> reported speech
present past
present perfect past perfect
past past perfect

China (original - has lifted) had lifted restrictions on the operations of foreign retailers as part of its WTO agreement

Some of Baleno's competitors (original - have already opened) had already opened directly managed stores in key locations.

Baleno's Fanchising Department (original - has also experienced) had also experienced severe staff shortage, with some staff leaving to help competitors in their franchising operations.