engram VS dnj-bigram

No problem, see this discussion on the Engram forums for more ideas on Q and Z placement: there are non-magical solutions such as combos, hold-taps, etc. In particular, this layout has been applied successfully to an even smaller 26+6 keyboard, as a precedent.

I've considered both the earlier version of APT, as well as Engram, with these layouts putting punctuation on the center index columns.

See my Engram 2.0 review as well as my programmer-friendly adaptation for details.

On leaving QWERTY, you might also consider Arno's Engram 2.0 layout, which places all punctuation in the central columns so that your 8 touch typing fingers go straight up and down, effectively staying in their columns all the time. I've used Engram exclusively since the past 2 years (after 6 months of BEAKL-15, 16 years of Dvorak, and 6 years of QWERTY) and I've written about my experience with it here. Moreover, if you prefer standard shifted pairs (e.g. so quotes don't shift into parentheses), I've created a programmer-friendly variant called the "Engrammer" layout that helps maintain cross-proficiency with standard keyboards.

And if you prefer standard shifted pairs (e.g. so quotes don't shift into parentheses), I've created a programmer-friendly variant called the "Engrammer" layout that helps maintain cross-proficiency with the standard shifting model.

The discussion on Github is here: https://github.com/binarybottle/engram/issues/46

Specifically, the main distinction between this layout and Arno's Engram, is that this layout retains standard shifting (e.g. Shift-Quote produces DoubleQuote rather than OpenParenthesis) in order to lower the cognitive barrier when having to use standard or non-programmable keyboards. This discussion elaborates further:

One of the few that acknowledge this is engram: https://github.com/binarybottle/engram

I've already talked with the dev to try to create a spanish variant of Engram, but since this is a subreddit of some keyboard layouts nerds like me who have some skills in creating layouts, I ask YOU if you could help create the perfect spanish layout. It's not easy, maybe too complex right now and there needs to be some adjustment... but come on, we NEED a spanish layout! 500 million of potential native writers will thank you for that in the long therm.