Microsoft Office 2011 – Compatibility with High Sierra

Yes, it appears to have been discontinued. Sorry.

Refer to the discussion at What happened to the Data Analysis Toolpak or Solver in Excel for Mac 2011? – answers.microsoft.com. Quote:

The Data Analysis Toolpak was removed in Office for Mac 2008. [emphasis mine] However, the following is a free third-party tool [...]

[... goes on to mention the StatPlus software you already mentioned ...]

See also: I can't find the Analysis ToolPak – Microsoft Office Mac Troubleshooting. Quote:

Cause: Excel 2011 does not include the Analysis ToolPak.

Solution: Download StatPlus:mac LE for free from AnalystSoft, and then use StatPlus:mac LE with Excel 2011.
...

That last link used to include loads of comments from disgruntled Office for Mac users, but Microsoft seems to have removed comment functionality from that help center article. Surely you can find disgruntled comments re: the above elsewhere on the net.

I've long experienced this problem, too. Haven't found any 'good' solutions, so put together some Applescripts that partially address the problem. It's very much a kludge and not a perfect solution, and deploying the scripts in a given user's workflow is a matter of individual taste.

Here's code to open an MS Word document in a space that doesn't have any Word windows without first triggering a shift to a space with a Word window open:

tell application "System Events" to tell process "Microsoft Word" to tell menu bar 1 to tell menu bar item 3 to tell menu 1 to click menu item 1 --open
tell application "Microsoft Word" to activate

And this script will close an MS Word document without triggering a switch to another space (if it was the last Word window open in the current space):

--Is there another window of the app in this space? If so, don't need to shift to another app before closing
tell application "System Events" to tell application process "Microsoft Word" to set _theWindows to name of every window as list
set WinNum to number of strings of _theWindows --(Office puts weird other things in the list)
if WinNum = 1 then --i.e., it is the only window in the space
    tell application "System Events" to keystroke tab using command down --switch to another app
    delay 0.1
    tell application "System Events" to set visible of application process "Microsoft Word" to true --in case there is a close dialog I still need to see
    delay 0.1
end if
tell application "System Events" to tell process "Microsoft Word" to tell menu bar 1 to tell menu bar item 3 to tell menu 1 to click menu item "Close" --close