You may be right, but I am having trouble with your interpretation of "colam" as "I pray". It clearly appears to be a 1ps future of colere. I do not think that you can impute that sense to colere. And if "haec" refers to the coin, then what word in Latin? The usual word "nummus" is masculine and would require "hic". That is why I said that the context is missing. What was the author thinking of when he used "haec"? I think you are correct about the front, but it could also mean "this happens at a good time".
All my translations are just "gut feelings". You might be right about the translation on the front. Maybe the haec refers to the raining on the plant.
I think the wheel with the broken axle is a symbol for "taking a risk" or luck. The rain on the plant probably is a symbol for luck.