Issue of irregular data, from multiple sources I have no control over

So, in my working environment, I'm usually tasked with making some sheets for specific needs that take as input data from up to 10 different sheets managed by different people in different ways, we're talking all manual formatting, different everything mostly, albeit very basic with close to no actual calculations, and of course no usage of advanced instruments.

My issue is - I always have to make uniform data from all that mess and then do my task, the first part takes 80% of time actually, so I wonder how I can automate that.

Examples of issues being, like, data written in different formats, same fields related to one person having slightly different data in nature or form in different sheets, namings not up to standards etc etc.

I absolutely can't influence other actors in any way.

I'm not sure how to tackle that issue mainly because I will need to somehow implement safeguads which will somehow track data conflicts, overlaps, duplication and such.

And second part is to somehow taking into account all types of slightly different ways data is represented among one type of data.

Will be grateful for any insights into how you deal with such chaos without ability to influence other people work processes.