Cant be injector seal if it coolant? Cant see but more like coolant pipe? Sitting in a big pile of pink liquid
Coolant pipe looks tight on wih no splits if indeed this is where the leak is but its ****ing all down the engine. No1 injector is the only well thats affected
depending on pressure loading pulling on it I have had good reliability with stud and bearing lock-provided it is a sliding fit and clean.
I used this on a nissan that the water pump pipe was supported and it has been fine.
So you're fist diagnosis was correct it was down to a period. Must have been as you have now found the crack it came from. A Dr Whites and insulation tape should sort it out.