This message should never appear, beginning with build 20694, when using Quark 2016 and above, as any box containing a BOXFIT token that does not have text overflow initially, will be automatically reduced in size to 3 points, to ensure text overflow, before the actual BOXFIT processing begins.
This diary generation message occurs before processing a BOXFIT token, if there is no text overflow to start with and if the warn if no overflow in boxfit generation option is set to true (the default).
➢Remember that the BoxFit token will only increase the size of its containing box; it will never shrink the box.
Therefore you should always make the textbox small enough in the template, so that text overflow occurs in all circumstances (unless you wish to have a minimum size, regardless of the contents).
If you wish to have the exact same functionality, but never see this message, then use the [BOXGROW] token instead.