Not sure why I'm posting, since this is definitely off the topic of TGC 2019, but ....
As ADX alludes, nothing can ever really be more than 100% - nothing. The only way you can consider something more than 100% is if you are using that percentage as a comparison to something less (like is often reported for company revenue from one period of time to another). So, in golf (be it IRL or a computer game) a swing that is 'more than 100%' is really only a swing that is more than a previous swing that wasn't 100%.
'Overswing' in a computer game is a term that is probably technically incorrect but stems from the old meters (vertical, horizontal or circular) where there was a line/indicator of a 'perfect' swing power. We all talk about that perfect swing power as 100%, but in fact it really was probably only 75 or 80% of maximum power. It might be 120% of the power what we normally try to achieve (note the comparison to the perceived perfect swing). Most of us have played golf games with similar power meters for upwards of 30-35 years. While I like my posts to be technically correct, I don't think it is required that they always are (and I'm sure they most certainly are not always technically correct!).
I keep up with a few threads over at HB's site, but I don't plan on buying/trying TGC 2019 until it significantly drops in price; my 8 hours with TGC1 was enough for me to decide I didn't want to purchase TGC2 or 2019. It sounds like some progress is being made with the physics, which is great, but my preference is for the look of JNPG (not Hacker Harry, though!).