You're right that "commit" normally takes an -ing clause rather than a bare infinitive, so your number 2 is better. But this is nothing to do with continuous tenses. "learning" here is acting as a verbal noun, as you can see in your example 3.
The difference with your 4, is not the "eat" versus "learn": it is about the frame verb. "Like" may take an infinitive with 'to' ("like to eat") or an -ing clause ("like eating fish"). "Commit" in this sense can only take an -ing clause.
[Actually there is a further complication, that there are two different meanings to "commit", which take different complements, and you're mixing them up.
If you use "commit" without a direct object, as you are, it means "promise" or "undertake" or "bind oneself", and can be followed by 'to' and a noun phrase (including an -ing clause) or by an infinitive with 'to'. So "I commit to learning English" or "I commit to learn English", meaning "I promise that I will learn English".
But that is not actually what you mean here, I think. You need "commit" with a direct object, meaning "dedicate some resources", and that cannot take an infinitive: "I commit time to learning English".
So what I think you mean is "I don't commit enough time to learning English". ]