I believe that this desire to ‘improve the Buddhas teachings’ is really the epitome of conceit of self, and is based on an incomplete understanding of what the Buddha actually taught. Unfortunately, it is only a tiny number of individuals (on a global scale) that have moved beyond these conditions and are able to know and see based on direct experience. For that very reason, I think the scholarship on the authenticity of the Buddhas teachings is so vital. The integrity of this scholarship is key, as the temptation (based on delusion) to think that the things one doesn’t agree with or understand must be corruptions, and to make those ‘corrections’ is always there in the background.
We know that there are some corruptions in the texts, and I hope that the knowledge of these will spread over time. Sadhu to all the careful sutta scholars working to achieve this 
In fact, just this morning I was discussing this, with regard to some ‘corrupted’ text involving the portrayal of women. The damage that these ‘corruptions’ do on both a personal and on a ‘sasana’ level is pretty awful to witness.
With regards to the OP I think it is imperative to be able to acknowledge what are the direct teachings of the Buddha, and what are later works that expand or modify the teachings. It is all about knowing the difference and then making an informed choice about which modes of practice to pursue. Otherwise, we are just willfully propagating delusion. Please Note this is nothing to do with judgments about good or bad - but just about being as clear as possible on the ascertainable facts. As always there are huge individual variations about what helps and what hinders progress on the Path at different times for different individuals. Informed choice doesn’t restrict choice, it is just about clear seeing.
With much metta 
