Building my personal phrase bank, would this be considered plagiarism? I have started to build my personal phrase bank since I’m a non-native speaker and struggling to build my arguments and sentences correctly. So I decided to mimic the structure of native authors who write in academia in general. To make it clear, I will provide an example: 

An established phrase from others’ work: 


  In recent years, it has become obvious that informal housing and land markets are not just the domain of the poor but that they are also important for...


My use of this phrase in my context: 


  In recent years, it has become popular that the idea of both big data and open data are important for the development discourse and not just as tools of the government.


I’m actually concerned whether this similarity in the sentence structure might be considered plagiarism.
I wouldn't immediately call it plagiarism, but there is something you are overlooking.


  Writing is not as formulaic as you think. Yes there are standard
  grammar structure, syntax, and punctuation, but when you put sentences
  together into a paragraph, the meaning changes. So when you put words
  in a phrase bank together, the end-meaning might not reflect what you
  intended.
  
  So when you put words in a phrase bank together, the end-meaning might
  not reflect what you intended. Yes there are standard grammar
  structure, syntax, and punctuation, but when you put sentences
  together into a paragraph, the meaning changes. Writing is not as formulaic as you think.


In your mind, 1+2=3 and 2+1=3, but in the case of reading comprehension, the sequence and order of which you read the sentences change the meaning. At the same time, not all "1" share the same meaning either so from time to time you would have phrases that seem out of place. As Alexander woo suggested, the best way to learn is to read, write, and practice.