A technique on other materials is to drill a very small hole at the end of the crack. That tends to stop the crack from getting longer.

For gluing canopies to airframes in new construction, RC-56 Canopy Glue or Weldbond work great. They might work, but maybe not great, on fixing a crack.

E-6000 is like a thinner version of Shoe Goo, and it is extremely handy for many things. I go through dozens of tubes each year. You can buy it at any Walmart or most any home center big box store. If the surfaces are properly cleaned, it sticks like a you-know-what, it is quite strong, and very flexible. If your canopy were mine, I would clean it very thoroughly with denatured or isopropyl alcohol, drill a 1/16" diameter hole at the end(s) of the crack(s), run a bead of E-6000 glue along the crack, then come back the next day to admire or fly it.