这里是不是有个“But that”的用法-“若非”?

题目

这里是不是有个“But that”的用法-“若非”?
Certainly their descriptions of battles are confused.But it is a little upsetting to read in the explanatory notes that a certain line describes a fight between a Turkish and a Bulgarian officer on a bridge off which they both fall into the river and then to find that the line consists of the noise of their falling and weights of the officers:"Pluff!Pluff! A hundred and eighty-five kilograms."

答案

当然,他们关于战斗的描述被混淆了.但是在这些解释笔记中它读起来有点烦乱,在这些笔记中,一些行描述了土耳其人和一个保加利亚警官在一个桥上 (在这座桥上,他们一起掉进了河) 的战斗,而且然后发现了那行描述他们掉下去的声音和警官体重:扑鲁,扑鲁,一百八十五公斤.
没有"若非"的用法.
1,explanatory notes 之后的 that 及其后到fall into the river,为一个定语从句,描述这些"explanatory notes解释笔记"中的内容.
2,But it is a little upsetting 包含了两个"困惑"的内容:
第一个是to read in the explanatory notes.
另一个是and then to and then to find that.
3,find后的that 为一个宾语从句,为find的内容（那行描述他们掉下去的声音和警官体重:扑鲁,扑鲁,一百八十五公斤.）
4.这个从句很复杂．套了两层．
notes的定语从句中,又包含一个定语从句off which they both fall into the river
而find的宾语从句没有再套．