If it aint' clicking, the problem isn't altitude. The clicking is the
impact mechanism hammering the piezo rock. Sounds like you need repair
or replacement. I love my TS4000 and use it regularly, but I'm at around
600'

Maybe so; maybe no.

Usually/often the "clink" occurs when the charge created by gradually
bending the crystal discharges (via the spark gap.)

If the gap is shorted, in many/most designs there just will not be a
"click."

At higher altitudes a spark will cross a gap at a much lower voltage.
But a low voltage spark just doesn't have the energy of a higher voltage
spark and may not ignite the fuel.

In any case, where you operate at extremes of moisture, air pressure,
and temperature, I believe you are better off with a flint type
lighter/igniter.