Yes, I know that many Amstrad users/developers do not speak Spanish. For that reason we decided to code in english. So, the code you can find in the Github repository is in English.
Also, you may try with translated subtitles. They are far from being perfect, but are an intermediate solution to the problem.
In any case, you may find the code we use and comment useful, even if you don't understand us speaking

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And, of course, you can ask me anything you need. As long as I have enough time, I will be here able to help if needed

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Note: In the same videos we also program in C using SDCC with CPCtelera

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