Office 2011 HAS been upgraded to 64-bit. First it was upgraded to Office 2016, which was 32-bit. Then it was upgraded to Office 2019, which was also 32-bit.
Office 2016 and Office 2019 are both still supported. Microsoft has provided a free upgrade from 32-bit to 64-bit for both applications.
All support ended for Office 2011 on October 10, 2017.
Every version of every software application ever made has a set of system requirements. I am sorry that I made the assumption that this is obvious and that everyone knows this fact. Software runs within the specifications. If you try to run the software
outside of specifications it may run, but most likely will fail, but whatever happens is not the responsibility of the manufacturer when specifications are not followed.
Every product, no matter what it is, has a product life cycle. It's made for a given period of time and then no longer. Product manufacturers offer various levels of support from no support to whatever support the manufacturer promises at the time of sale.
The product life cycle of Office 2011 was 12/9/2010 through 10/10/2017. This time frame was extended from a much shorter 3-year time frame that was announced when Office 2011 was introduced. You can find the life cycle policy for all Microsoft products here:
Microsoft Lifecycle Policy
Microsoft's OS support policy has been consistent for Microsoft Office on both Windows and Mac for more than 30 years. The current OS version plus 2 back are supported at any given time during the product life cycle. For Office 2011 that means that Mac OS
versions 10.5.8 are supported through whatever version of Mac OS was the latest on 10/10/2017. Apple has kept Mac OS going in such a way that Office 2011 continues to run in all versions of Mac OS up to and including 10.14. Apple decided to dump support
for Office 2011 and all other 32-bit applications, drivers, software and hardware with Mac OS 10.15 Catalina. Personally, I don't think Apple did a good job explaining to ugraders the ramifications of that policy in terms of what will no longer run in Mac
OS.
Even within Office 2019, the introduction of Catalina has ramifications for support. Version 16.30 and later requires Mac OS 10.13 and newer.