Hello,

You can enable Customer and Vendor visibility restriction and this does apply based on the logged in branch.  This doesn’t solve all the issues you’ve listed above, but does address some of the points you raised.  

Here’s the Acumatica Documentation from the customer side (Vendors works in the same way):  https://help.acumatica.com/(W(4))/Help?ScreenId=ShowWiki&pageid=2828845f-1fd4-4c37-806e-3406cb57b72e

I did a video on this when they released the vendor side of things in 2021 (Customer restriction existed a few versions before that) 

You can also restrict cash accounts by branch on the Cash Accounts form to prevent picking incorrect bank accounts based on the logged in branch.

But other than that, if a user has access to multiple branches, they will be able to see all data for all the branches they have access to on any screen.  For reports, most will default to the logged in branch and you can add various filters by branch onto generic inquiries to make it easier to see just information for a single branch at a time.

I think that is the issue here that we do not have any flexibility to say that Users should only see Data of the Branch they are logged into when they have access to multiple Branches. 
Not saying this is a design flaw, but I wish they would’ve considered this very common usecase for this.
I thought some of our clients were the only ones asking for it, but looking through the Forums, this is very common.

I have a Support case open to see if there is a recommendation, otherwise I’ll create an Idea and hope we can gain some traction on this.