Several years ago, I wrote a large application for the CSIRO which, each quarter, imports about 25 reports in the form of multi-sheet Excel spreadsheets, consolidates and processes the data in them and exports a wide range of reports as fully-formatted Excel spreadsheets, some of which are multi-sheeted. All of this is done by clicking a few buttons in Panorama 6 forms. The spreadsheets are converted to text files by Excel macros and the reports are formatted by macros, all under the control of Panorama 6. The macros are written in Excel for Mac 2011 and the whole thing seems to run quite well in Panorama X in macOS Sierra (I've only run a few checks because of the size of the package but it all looks OK).
And, of course, it runs like a Swiss watch in Panorama 6 - there hasn't been a problem for some four or five years.
If anybody has a need for anything like this, I'm happy to pass on my knowledge - it was a long and steep learning curve and it seems a pity to waste it.