Iriyāpatha and sampajañña

1. It's the outspoken translation. Nothing is wrong by the context. See Ruben's answer.
2. However, the obvious serious wrong is the vocabulary translation. Pajānāti means "comprehension", it doesn't means "know".

Furthermore, when a mendicant is walking they know comprehension: ‘I am walking.’
Puna caparaṃ, bhikkhave, bhikkhu gacchanto vā ‘gacchāmī’ti pajānāti

3. The Atthakathā explains the comprehension, Sampajañña, to four here. These four comprehensions have two levels:
   3.1. The samatha level in MN KāyagatāsatiSutta which taught to the beginner, neyya. The listeners in this Sutta are the newbies, so the Sutta's structure point to Jhāna, CittaVisuddhi, at the end of each section.
   The practitioner begins by ĀnāpanassatiJhāna in sitting meditation, and keep to meditate Ānāpānassati in Section on postures and Section on sampajañña. This is the basis.
   3.2. The vipassana level in MN MahāsitipaṭṭhānaSutta which taught to the high level vipassanā practitioners, ugghaṭitaññū, in Kuru Kingdom. All of the listeners in this Sutta already practiced these 21 sections, but the end of each section, samudayavayadhammānupassivā dhammasamiṃ Viharati (the practitioner comprehensions the origin and the cessation in all practiced practices and the comprehending mind), is their last lesson of the practice, so MahāAtthakatha said many listeners enlightened as Arahanta after the listening.
   This level appeared in explained in MN MahāsitipaṭṭhānaSutta's Atthakathā. It's not for the beginner. If the beginner start from this explanation, he is going to stick at the 10 imperfections/defilements of insight, Vipassanūpakkilesa. This explanation is very popular however most of teachers, today, give it the the improper practitioners.
   That's why most of them can't enlighten in seven years according to the end of this Sutta. The sequence level is very important, when the practitioner cross the sequence, it means the defilements of insight still remain.
   The question owner creates this question because he thinks follow to this level.
4. the meaning of the comprehends is the same as above wiki link, except the fourth.
   4.1. The sampajañña of samatha level is...
   

   when a mendicant is walking they comprehends: ‘I am walking for the purpose, suitability, and domain of the non-delusion in the breath meditation’.

   4.2 The sampajañña of vipassanā level is...
   

   when a mendicant is walking they comprehends: ‘I am walking for the purpose, suitability, and domain of the non-delusion in the aggregates in the Dependent Origination cycle’.

   4.3 How can I know that explanation?
   I understand it from Sutta context after I recited and memorized MahāsatipaṭṭhānaSutta Pali for ten years (so I often tell you all to memorize the pāli to study Sutta). The context is already arranged from the basic to the advance like in the explanation in Netti.
   Pajānāti has already appeared before the Section on postures in the summary Section of this sutta, Ānapanassati Section, and almost all other Sections as well. It means the Section on postures must translate with those all sections as I translated above.
   So, what is written in wikipedia, it is wrong...
   

   While the nikayas do not The Sutta has already elaborated on what the Buddha meant by sampajañña as "the keeping comprehension of current meditation in four main postures and seven sub-postures", the Pali commentaries analyze explain it further in terms of four contexts for one's comprehension

   Actually, pajānāti and sampajañña is already elaborated in Sutta's context clearly already.