Electrical – Can reverse voltage gain for a BJT be negative

You've got two lots of miller capacitance to factor in here. The output stage miller cap is shunting the collector resistor thus reducing the gain at higher frequencies. Also the first transistor's miller capacitance is acting as a shunt to the collector resistor too.

You've got the tools right there - try seeing what the performance is with the 2nd transistor removed - does this improve the frequency response (maybe it will double it to about 6 MHz). Plenty of things you can generally do with a simulator that allows you to focus on a problem.

It's not worth trying to compensate for the gain roll-off - better to choose an improved BJT.

EDIT - just so there's no confusion. I'm saying "no" to miller effect but "yes" to miller capacitance affecting the high frequencies by shunting the collector resistor. AFAIK, miller effect is due to the miller capacitor causing feedback to the base but, because the base driving impedance is low (probably close to zero in the OP's simulation), the miller effect is minimal.

Of course, for infinite YL (short circuit) the gain is zero. Hence, you are right and the authors of the book book made an error (typo?). Without any external load resistance (ZL infinite), which applies, for example, to a very (nonrealistic) inductance and a corresponding high frequency, the gain would approach a value that is determined by the internal output resistance ro=1/ho of the transistor only. However, that´s a theoretical exercise only.