How do you use Codex? Via the web interface, the JavaScript adapter function, or the shell program? You also mentioned ChatGPT at one point.

When I use Codex via the shell program, I get excellent results. Very often, the output is right the first time—or requires at most one or two minor corrections.

With the JavaScript adapter function (does that even use Codex?), a relatively large prompt is transmitted alongside your actual instructions.

When using the web interface, Codex has to gather the necessary information first, which also consumes (input) tokens.

I would recommend using Codex via the shell and asking it to create a "skill" for ioBroker scripts.
It then saves this in the appropriate directory for future use.

If Codex does things you don't want it to, just tell it so or modify the skill (or have it modified).

The same applies if Codex implements things that are incompatible with ioBroker.

Over time, it causes fewer issues.
That said, my results are actually very good even without using a skill.

You mentioned that it consumes a lot of tokens—could you explain that in a bit more detail?
In my experience, consumption stays within reasonable limits.
It’s also important to ensure the context fill level doesn't drop too far below 50%; that’s when you start getting nonsensical or unnecessary results.