Is it considered a divorce for the husband if he wrote to a fatwa website about a previous divorce, based on an indecisive stance, knowing that writing is considered a metaphorical expression (kinayah) and requires intention, and that informing (ikhbar) is not considered an initiation (insha’) unless the intention behind it was initiation?

The fundamental principle is that the marital bond remains intact unless there is certainty to the contrary, in accordance with the jurisprudential rule: "Certainty is not removed by doubt." So, if you doubt the intention of an allusive divorce, the default is that there was no intention of divorce, and the marital bond remains valid. As for your utterance of "I take her back" as a precaution due to doubt about the occurrence of divorce, this does not result in divorce. Nor does divorce occur by recounting a previous divorce without the intention of creating a new one.