Soldering time for HC49 through-hole crystal without damaging it
Is there a limit on how long the hot solder tip can touch the crystal lead before a crystal malfunctions?


Yes, but its absurdly long.  If you get two or three data sheets for comparable crystals from two or three reputable crystal manufacturers then you should find some guidance, and it should more or less apply to any decent crystal.

Basically, if you're not destroying your TO-92 cased transistors, and if you're not subjecting your crystals to mechanical stress, then your crystals will be fine.