一个英语句子语法问题!The past several years have witnessed a phenomeno

语法没有什么错误,就是个别字眼需要斟酌一下,用字不要显得太学究气,要平易近人为好.
universally 最好替换成 widely.另外在逻辑上有点不适当的地方,就是 for the reason 本身就是指代了前面省略号说的一大段的原因了,你这里还要引用一个that的同位语从句来继续讲这个原因做什么呢?这嘴碎的,太 wordy 啦!最后的 which 引导的非限定性定语从句还是可以接受的.
最后可以改为：
The past several years have witnessed a phenomenon that . ,for that reason, it is widely acknowledged that taking care of our parents is a virtue, which should be accepted, respected, appreciated and advocated.

最近几年见证了……的现象，原因是……………… 句子的主干应该是这个吧，感觉有点不符合逻辑呢。你想要表达什么意思呢？咋一看语法是没问题的，无非是从句套从句套了很多从句……这样的句子其实是有些不符合表达的习惯的，太长了…… is universally acknowledged that 这个句子感觉就没必要了，显得冗长。...

witnessed改为shown，其他的没发现有错的

别扭。非限制性定语从句which should be accepted,respected,appreciated and advocated惹的祸，它只是用来指代 taking care of our parents is a virtue，直接括起来得了。
for the reason that it is universally acknowledged that taking ca...

没有语法错误，但是很别扭，不容易知道你想表达什么。不如把它写成两句话。
The past several years have witnessed a phenomenon that .....。The reason why this happened is taking care of our arents is a virtue, which should be acccepted, respected, appreciated, and advocated.