Two 5-cannons plus two medium lasers plus two 2-cannons (5+5+5+5+2+2) adds up to 24, which in Alpha Strike becomes 2.4, rounding up to 3. The Jagermech 6-S doesn't have any heat issues worth caring about, so there's no reduction there.

Similarly, the long range damage comes from all four cannons (5+5+2+2) for a total of 14, becoming 1.4, rounding up to 2. The cannons will suffer minimum-range-related penalties at short range, but if the total remains above 2.0 by even the smallest fraction, it will still round up to 3.

The rounding-up nature of the conversion process means that almost every Intro-tech unit that relies on smaller autocannons gains immensely in combat utility in Alpha Strike as compared to standard Battletech, because they often just barely meet thresholds to round up their damage ratings.