It is hard to evaluate likelihood of problems with higher than label dosages of forskolin carbonate as we have not studied it and it is hard to do even for forskolin itself.
The only formal studies I think are Sabinsa’s, which are no higher than 25 mg 2x/day.
While it’s hardly authoritative, I did try searching the Internet to find testimonies on use at higher dosages. This proved really problematic because the intelligence level of the people writing seemed usually to be similar to that of Youtube commenters, with one of the results being that the typical thing was to refer to milligrams of EXTRACT without bothering to mention concentration of the extract.
However from what little I found, there were some complaints at doses of 50 mg forskolin at a time. No major events.
Another source of information, but a poorer one than one might expect, is US patents. There are some US patents claiming testing of doses of forskolin considerably higher than Sabinsa’s – I forget what but they may have been 100 mg at a time or more – and claiming no particular problems. However, it’s a mistake to rely on testing claims found in patent applications. But I would take it as evidence that some can get away with this for forskolin itself.
If you want an n=1 data point, I personally have not the slightest trouble with three Carbolin 19 capsules at a time, which is 60 mg. However, comparing to other users at Biotest, I seem to have higher tolerance than most people.