I'm wondering if it might be helpful for you to have a book like "amazing glaze" hanging about in the studio - guessing it's you or someone without kiln knowledge who is loading the kiln, and it's going to be helpful to learn about kiln cookies/wadding/testing/firing safely so that your glaze doesn't turn up on the kiln shelf.
AG: https://www.amazon.com/Amazing-Glaze-Techniques-Recipes-Finishing/dp/0760361037
re: not being US based - guessing amaco will have a distributor. Feel free to DM me if you get stuck and need help.
Check out GabrIel Kleine’s clear glaze. It’s SO easy and never had any issues. Thick, thin, I’ve tested it successfully cone 3-6. So so clear every time.
I don’t know if the recipe is published online but it’s from this book https://www.amazon.com/Amazing-Glaze-Techniques-Recipes-Finishing/dp/0760361037/ref=nodl_
Glaze manufacturers have them eg: mayco
https://www.maycocolors.com/glaze-combinations/
Because there's so many variables with glazes, it's tricky, and that's probably why its best to test yourself - you're going to need to do it anyway. I haven't checked glazy.org for these, but the book amazing glaze has recipes and end results with glazes that are made to go over others: https://www.amazon.com/Amazing-Glaze-Techniques-Recipes-Finishing/dp/0760361037
it's hard to say what is causing the flaking without seeing the piece and the thickness of each layer. I'm guessing that's it's your application, and something might be too thick.
Test tiles:
https://ceramicartsnetwork.org/daily/pottery-making-techniques/ceramic-glazing-techniques/tips-for-making-the-right-test-tiles-for-testing-your-glazes/
If you're new to glazes, this is a new book from an american based author (which is edited and forwarded by John Britt above...):
https://www.amazon.com/Amazing-Glaze-Techniques-Recipes-Finishing/dp/0760361037
hope that helps.
Preemptive: If you end up wanting to wash everything off and start again, wondering if hot water/hair dryer/something to get that layer of wax off, so then you can remove the glaze underneath (particularly if its too thick) could be helpful.