@SnO3 I have rarely come across a series in which both a machine translation and an actual translation occur for the same chapter and here are some possible scenarios when it comes to translations.
1) The series is less popular and so no actually knowledgable translator chooses to work on it. Thus we only get mtl.
2) The series is very popular and already has a translator/group working on it. Some groups even just forgo a true translator, and use mtl as a helpful tool with a translator with limited knowledge. Thus we get only a translator.
3) Series of varying popularities have the original group with a translator stop uploading for a while. This can cause a couple things to happen:
3a) A mtl comes in, and either prompts a public announcement from the original group (if there was not one already) or the original group retranslates the mtl chapter if they feel it has lacking quality or misses some key points. Thus we get both mtl and translator.
3b) Another translator steps in (either from within the group or from outside the group) and takes over. This can either lead to childish drama, multiple translations at once, or collaboration. Thus we have a translator.
4) A translator decides that the mtl was of a sufficient quality and hit the correct key points. They then decide to not retranslate the same chapter, and move onto the next chapter.
Never have i seen a series get a shitty mtl and then a decent translation that decides to not redo the shitty chapters. The people from the MD discord have nearly unfounded concerns, and do not have any power over you or your translations unless they have a role in the discord of: Admin, Developer, Moderator, Public Relations, or Designer.
TL;DR: if their role on the discord server is none of the actual staff roles, their opinion meets jack shit when it comes to what you decide to do. This is not to say you cannot take it into consideration, but put their opinion far far below your own opinion of the matter. That includes me since I am not a site staff.