Learn Dutch: Als hij de tekst deletete, zouden we hem weer editen. - If he deleted the text, we would edit it again.

It is actually correct. For English loan verbs, Dutch applies the standard 't kofschip rule based on the pronunciation of the English stem. The stem of deleten is delete, which ends in a /t/ sound. Because the /t/ sound is in 't kofschip, we add -te for the singular past tense. This results in the awkward-looking spelling deletete.

Why is the infinitive editen instead of editten? Doesn't a short vowel usually force a double consonant?

Normally, yes. However, the word stress in editen falls on the first syllable. In Dutch spelling, if the vowel just before the final consonant is unstressed, the consonant does not double. This is the exact same rule that gives us monniken instead of monnikken.

Why does zouden come immediately after the comma?

This is an example of inversion caused by a subordinate clause. The entire als clause acts as the first conceptual building block in the main sentence. To maintain the V2 (verb second) rule, the conjugated verb zouden must take the second position, which places it right after the comma.

Why do we use the pronoun hem to mean the English word it when referring to the text?