Bhante Anandajoti has kindly provided another translation of the cited teaching in Suppabuddhassa kuṭṭhissa, which changed my understanding of the fetter of doubt and the "Dhamma eye":
to the leper Suppabuddha
"tasmiṁ yeva āsane virajaṁ vītamalaṁ Dhammacakkhuṁ udapādi:
on that very seat, the dust-free, stainless Vision-of-the-Dhamma arose:
“Yaṁ kiñci samudayadhammaṁ, sabbaṁ taṁ nirodhadhamman-ti.”
“Whatever has the nature of arising, all that has the nature of ceasing.”
Atha kho Suppabuddho kuṭṭhi diṭṭhadhammo pattadhammo
Then the leper Suppabuddha having seen the Dhamma, attained the Dhamma,
viditadhammo pariyogāḷhadhammo tiṇṇavicikiccho vigatakathaṁkatho
understood the Dhamma, penetrated the Dhamma, crossed over uncertainty, being without doubts,
vesārajjappatto aparappaccayo Satthusāsane, ...
attained full confidence, having become independent of others in the Teacher's teaching, ..."
I agree with Bhante that what the leper Suppabuddha is not in doubt about is the veracity of the teaching -- specifically about the nature of the 2nd and 3rd noble truths, or conditionality, which is in accordance with the previously cited SN Chapter IV - 25 Okkantisaṃyutta Connected Discourses on Entering. The comprehension of the first three NT will irreversibly lead to the understanding of the 4th North Truth, and the breaking of the three fetters.
I suppose that this obtaining of "the Dhamma eye" (the vision of the Dhamma) would make the leper obtain the first stage of the enlightenment, not the second. I don't imagine that he could have comprehended the 4th Noble Truth -- the Noble 8-factored Path within that short moment. The comprehension of the 4th Noble Truth would mean that one has penetrated all 8 factors and has entered the path, or reached the second stage of the enlightenment, to my understanding.
Thanks for Mkoll's input, and welcome more. Metta to all!
PS: I recommend Bhante Anandajoti's sutta translations containing both Pali and English, which I believe are closer to the original meaning and can be found using the search engine: http://www.ancient-buddhist-texts.net/