So, for example, let's say that a bid comes in for Welsh in the 4th round, say at pick 50. Pick 50 is worth 273 points. We get a 20% discount, so take 54 points off that. Hence we have to give up picks totalling 219 points.
We have pick 64, which is only worth 101 points. Our later picks aren't worth any points at all. So we would be in deficit 118 points. Let's say next year our 4th round pick is pick 55, which is worth 207 points. Instead, that pick would be replaced by a pick worth 207 - 118 = 89 points, which is roughly pick 65 instead.
(Realistically, on the night, our picks would likely have moved up the order because of other teams matching bids and losing their picks as a result, so our pick 64 will probably actually be worth more than 101 points, and our later picks might even have some value. But we're getting in the weeds now.)
We have pick 64, which is only worth 101 points. Our later picks aren't worth any points at all. So we would be in deficit 118 points. Let's say next year our 4th round pick is pick 55, which is worth 207 points. Instead, that pick would be replaced by a pick worth 207 - 118 = 89 points, which is roughly pick 65 instead.
(Realistically, on the night, our picks would likely have moved up the order because of other teams matching bids and losing their picks as a result, so our pick 64 will probably actually be worth more than 101 points, and our later picks might even have some value. But we're getting in the weeds now.)