Sentences that begin with infinitve.

Yes, I think they are grammatically correct, just strange choices of verbs.

These are grammatically correct in English, but they are not good translations of the Spanish.

The main problem is with "andar", which just cannot be translated as "walk" in these contexts.

I think I would translate the Spanish like this:

Once you know how to read, you can be a success.
If you have ever loved, you've learned how to deal with life.

These are "off the top of my head" translations. I did them too quickly, perhaps, but I think you get the basic idea that "walk" has nothing to do with the meaning of the Spanish.

Hope that helped!

No I disagree. I'm a native English speaker and the original sentence had no coherent meaning for me. 'Walk' cannot be used as a metaphor in that way. 'Learn to walk before you run' works as a metaphor for learning the basics before trying the difficult stuff, purely as 'walk' does relate to 'run'. You do actually learn to walk first, then learn to run.

Walk has no connection with 'love' or any other of the phrases given before, so it is nonsensical.

A phrase comparing an early stage of an activity to a later stage of an activity only works if the second realistically follows on from the first.

To say 'learn to walk before you scuba dive' is daft.
'Learn to swim before you scuba dive' works, but only if it is an instruction to someone wanting to scuba dive. You wouldn't just substitute it for 'walk before run' as a metaphor for a completely different situation. You can't just switch the words in a metaphor/idiom and expect it to still work, because it doesn't.

In sentence (1), we need a 'going' verb that will permit the contrast with 'ascender' in the second half of the aphorism (= 'saber escribir es saber ascender', which isn't given here). It must therefore be a pedestrian verb, as 'leer/read' is the pedestrian activity in this comparison.

I'm not sure I see the objection to 'walk'. It's already used in a similar way in 'walk before you can run'. Eladio's translation has the virtue of allowing a natural transition into 'saber...ascender'.

I agree with Nona that some readers would find 'read...walk' nonsensical. That's how the antithesis works: the puzzle of 'saber...andar' is resolved by 'saber...ascender'. So if you only have the first part of the aphorism (as above), you only have the puzzle.

It's interesting to note that Jim's translation makes 'leer...andar' self-contained. This could create problems when translating the 'escribir...ascender' half of the antithesis.

Sentence (2) is quite another matter, & may well require a different English verb.