Umm this doesn't make sense.
SO if you use sugar from another source like sugar cane, the beer doesn't contain cane sugar, only alcohol from when it did, so that is OK.
If you add cloves or bananas to beer and the finished product only has the flavour from these additives and not the actual fruit then that is OK as well?
Granted there wasn't SS in 1516, but the beer doesn't have its flavour modified from SS or steel tanks and the oak that they used back in the day was internally coated so that it sealed better and DIDN'T pick oak flavour and was alot more hygenic.
The beer will contain tannins from oak and other flavour compounds (so it does contain oak) this can be easily proven.
In my opinion if you use anything other malt, hops, water and yeast to modify the flavour than you can't quote the 1516 rule and use it in your marketing.