Went past my old plot walking the dog, looking very neglected now! My successor has been kicked off the plot for not maintaining it to a decent standard. All that work I put in undone!

I've grown my U K up a trellis this year, for the first time, and they've not done very well at all. Only 1 or 2 fruits per plant.
I used to get 3 or more when I grew them on the flat on my allotment. Mind you the weather hasn't been good for them this year, so I suppose it could just be that 
Back to in the ground again, next year, though 

I've looked back at photos from previous years when the vertically grown plants did much better, I suspect that you may be correct in that the very wet and cool early summer this year didn't help. I was able to devote a large section of the plot to squash as I had to lift the spuds early due to blight, every cloud .....

When I Grow Up - Pussycat Dolls

Fisticuffs In Frederick Street -Toy Dolls

The report doesn’t mention watering, that’s my conjecture as to why the germination rate is higher. You can water Bustaseed trays from the top and soak conventional modules from the base.
Base watering of trays is a standard amongst professional horticulturalists and has been for some years. I hadn’t heard about not using the method in peat-free composts but note Melcourt Industries do composted bark products so maybe they don’t use coir (the commonest peat-free compost base) which probably works differently with regard to capillary action.
The report was produced by Queen’s University in Belfast which is in Northern Ireland and differs from the rest of the UK due to the EU settlement. So, they are free to use peat composts as are most of the EU. Ireland is a major producer and exporter of peat.
I’m hopeful that the current governments expressed desire to operate more closely to EU regulations could result in peat re-appearing in the garden centres.
I believe the composts used were peat, New Leaf and Pro-line which is a commercial organic compost.