Yeah it's very annoying reporting a bug and just being told it's 'working as intended' when it blatently isn't - I had a very long argument to get the Ventilation controller bug acknowledged several releases ago: it simply stopped functioning for "Cooling support" mode. I had various erroneous push backs from Loxone, from them saying it wasn't intended for that (despite the website advertising this very feature as an eneergy saving benefit of loxone), or that cooling support only works if you have a CO2 sensor (which is obviously not necessary, nor effective to fix it).
Having said all that, in this case I do still think you'd be better off not using Alarm Clock blocks: since you don't want them surfaced in the UI they're overkill for the job. I agree there's no performance benefit to getting rid of them, but there can be a stability benefit in using the less complex blocks. I avoid using the complex UI blocks unless I actually want that specific UI.
For this scenario my go-to would be a couple "Pulse At" blocks, and either have the radio button control their Off input, or filter the output with AND gate:
(The whole AND/OR ladder could be reduced to a single IF() Formula block desired). The "pulse at" duration can be adjusted so the monoflop is probably redundant too.
None of that excuses the fact DisA input has broken for you.
If keeping with the Alarm Clock, you could try using the OFF input rather than DisA ?