Support for filters was improved in one of our recent updates, are you using the same version as the one that we have listed in our Help Center article here?
The issue was a result of Data Studio applying processing when using filters, we solved it by adding filters directly to queries for our Analytics.
With regards to the second point - duplicates - we’re releasing an update later this week that will address this issue of dimensions not being aggregated in a table (campaign names showing up twice in results and so on).
I created a new connection yesterday from the link in the Help Center.
Even if I use explore on the connection and only apply a date filter on “Goal name” and “Goal revenue”, the values are wrong Screenshot by Lightshot
We’ll try to reproduce your issue. We are aware of an issue when using Goal name (it will also be fixed later this week), we’ll verify if it’s exactly what’s causing this discrepancy.