One of the problems, for me, over the catalyst theory (which you pretty much just re-iterated), is there are many statements, from Joseph Smith that he was "translating". As you note, this is not what he did with the Bible (nor what he claimed to do).
We used to call that a SWAG.
Sorry that I did not get into the Book of Abraham debate. What does SWAG stand for.
D&C 73: 3-4
3 Now, verily I say unto you my servants, Joseph Smith, Jun., and Sidney Rigdon, saith the Lord, it is expedient to translate again;
4 And, inasmuch as it is practicable, to preach in the regions round about until conference; and after that it is expedient to continue the work of translation until it be finished.
Joseph Smith definitely saw himself translating the Bible by combing through it, looking unto the Lord in every thought.
The Lord told Hyrum Smith while the Book of Mormon was being worked upon how the work is accomplished.D&C 11: 19, 22
19 Yea, cleave unto me with all your heart, that you may assist in bringing to light those things of which has been spoken—yea, the translation of my work; be patient until you shall accomplish it.
If you think about Joseph Smith's translating techniques he never comprehended the Book of Mormon script and did not pretend to be able to read it. He relied upon revelations.
When Oliver Cowdery attempted to translate he failed because he did not understand the rudiments of getting a revelation from God. The "studying-it-out-in-your-mind" aspect, the same as "cleaving unto me with all your heart".
What that is as per my own experience is a diligence in keeping the intent to received a revelation firm in your mind and purposefully in your heart and else-wise always cooking on the back burner in your desire to know which demands that you apply your faith constantly fixed upon the object of your inquiry. This "study" is floated up before the Lord in your constant prayer for an answer.
Joseph Smith never gave out about being a linguist who could decipher the Book of Mormon glyphs. The sacredness of the Gold Plates would cause him not to want to make it common.
It would appear that he was striving to learn Egyptian. I see him roasting the papyri on the back burner with a desire to unlock a mystery hidden in them. BANG! He gets the revelation of the Book of Abraham. To Joseph's mind getting a revelation while concentrating upon something counts for a translation.
Joseph was told that his name would be had for good and ill. Or that there would be both good and evil spoken of him. The Book of Mormon is that good part and the Book of Abraham has certainly become the evil part, where so many are convinced that he conned everyone, and therefore their faith collapses and they can only think evil of Joseph Smith thereafter.
Back in the days when I was striving to fix LDS problems that arose from scriptural ignorance this Book of Abraham was not the bugbear it is today. For my great love of the prophet Joseph Smith I should take the time to fix this. My faith tells me that there is a purpose here that the Book of Abraham demands.