These calculations are incorrect as well.
100sec unit, 20% French reduction = 80sec, or 20% reduction in original training time, ie, ((80-100)/100)*100=20% decrease
TB non-French = 23sec, or 77% reduction in original time
TB French = 3sec, or 97% reduction in original time
The straight time comparison is 7.67x, but the percentage comparison is 1.26x: 3sec*7.67=23sec and 77%*1.26=97%
You can't simply convert 'times faster' to a percentage by multiplying it by 100.
Therefore, French armies are built 7.7 times faster, or 87% faster, than non-French armies, all using a TB, in this scenario.