It looks like you've kitted this like a GMK keycap set. I would suggest looking at the conventions of other ePBT sets that have run. There are reasons for the differences, notably the permissiveness of MOQ and price with ePBT compared to GMK. As it is, this is kind of a "shooting yourself in the foot" situation.
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I will speak with ePBT about this, they seemed happy running it with the current kitting
Like Lfgberg said, the issue is not that ePBT won't run it. ePBT largely does not care what your kitting looks like.
GMK kitting is a large series of compromises based on high price, high base and child MOQs, and limitations of doubleshot ABS keycaps.
In contrast, ePBT has a MOQ of 200 for a base set, and all child kits are made if the base kit is made.
This does not mean that you need 35 kits like a KAT set with three distinct colorways, but it also opens up a lot of possibilities, considering there is not a significant markup on child kits, e.g.:
* Your 40s kit can be more supportive
* numpad can be its own kit without being cost prohibitive for those that want it.
* spacebar kits are cheap as hell and can be very accommodating
* "extension" kits like the one you have there are unnecessary. those are a direct result of the "compromises" required of GMK
* international layouts are easier to accommoodate
Again, I highly recommend looking at the patterns in the other sets running this year. Following the formula others have used will allow you to reduce base price without disenfranchising users of more popular child kits (like numpad) or niche layouts, which will in turn increase interest.