Is that library specifically meant for the tiny x5 series? The timers available on the x5 are significantly different from those available on other attiny boards.
Also - whenever you use any servo library, it's going to take out some of the PWM outputs (1 or 2 on the x5 series, depending on whether it uses timer0 (which will also take out millis() ) or timer1 (which is totally unlike timer1 on any other AVR micro other than the tiny x61 series)