Is the Tipitaka considered infallible in Theravada Buddhism?

It’s infallible in the same way that a car repair manual is infallible. The instructions provided therein are for the maintenance and proper use of your mind in the context of Buddhist practice. If you elect to drive or service a different vehicle, they’re of little use. Likewise, any musings in the sutras that aren’t about Buddhist practice (e.g. cosmology) aren’t always taken at face value just as I wouldn’t necessarily trust a car repair manual writer who started musing about the best way to fry a donut. His opinions may be valid, but it’s not his area of expertise.

It is not supposed to be infallible, it is supposed to be experienced and understood through actual practice.

Most of what is taught in the tipitika, the actual practical advise is meant to be put into practice to see its merits, not intellectually understood or just believed, like the bible quotes you have posted.

Assuming you have not studied the tipitika, I will state that Buddhas teachings are empirical evidence of reality, where as christs teachings are often pleasant platitudes and most of the bibles statements are simply belief orientated content.

Still there is wisdom in the bible as well as similarities with the Buddhas teachings Corinthians 12:15 seeming to be sunyata explanation for an example.

(some theories is that christ studied with the essenes in the road to damascus story, with the essenes being generally accepted as a sect of Buddhists)

According to the Tipitaka -- more specifically the suttas -- the Buddha himself explained how to assess whether something is true.

• One is, "when you know for yourselves" -- see for example Kalama Sutta including the Translator's note
• Another is The Four Great References, which implies that sentences should be:
  • "studied"
  • "traceable in the Discourses" (which I think means, "matching what's said elsewhere")
  • "verifiable by the Discipline" (which I think means, "can be experienced in practice")

A couple of examples:

• This answer summarises a study -- by academics, who are not that I know of monks -- of a very minor element of doctrine, i.e of one list-item in a list, which suggests this list-item is maybe a later insertion and not original doctrine of the Buddha (including for reasons given in the Four Great References)
• This answer by a monk suggests that some people take some parts more literally than perhaps they should
• This answer lists examples of various "suttas of indirect meaning" i.e. which people might misunderstand unless they're properly explained -- so apparently, even if the Tipitaka itself were infallible, the audience interpreting it are not necessarily.

Perhaps the idea of infallibility -- e.g. that it's conceivable or that it's important question -- belongs more to "people of the Book" e.g. "papal infallibility" by the Catholics, "biblical fundamentalism" by others, the Koran being literally the word of God, and so on.

I think that some have respect for the Vinaya at least -- taking every word of that literally.

The noble disciple has faith in the Dhamma (the teachings), including in the truth of the Dhamma, and also takes refuge in the Dhamma.

"He (the noble disciple) possesses unwavering faith in the Dhamma thus: 'Well propounded by the Blessed One is the Dhamma, evident, timeless, inviting investigation, leading to emancipation, to be comprehended by the wise, each for himself.'
DN 16

A Dhamma follower accepts the Dhamma only after learning it, and reflecting upon it.

“What kind of person is a Dhamma-follower? ... but those teachings proclaimed by the Tathāgata are accepted by him after reflecting on them sufficiently with wisdom. Furthermore, he has these qualities: the faith faculty, the energy faculty, the mindfulness faculty, the concentration faculty, and the wisdom faculty. This kind of person is called a Dhamma-follower.
MN 70

But the Tipitaka is not the same as the Dhamma.

Monks and lay followers don't consider the Tipitaka infallible or incorruptible. The words of the Buddha as written in the suttas are not considered the verbatim words of the Buddha, as they may have been paraphrased for ease of memorization (please see this answer for details). Furthermore, the Buddha did not speak Pali. Rather he spoke Prakrit dialects similar to it.

The meaning is more important than the phrasing:

The venerable ones agree about the meaning but differ about the phrasing. The venerable ones should know that it is for this reason that there is agreement about the meaning but difference about the phrasing. But the phrasing is a mere trifle. Let the venerable ones not fall into a dispute over a mere trifle.’
MN 103

Sometimes, later additions to the Tipitaka are acknowledged by the Tipitaka commentaries. You can probably consider them counterfeit, but they are few and insignificant.

There may also be minor contradictions between some suttas.

The most important point is that the Dhamma can be understood from a significantly large part of the Tipitaka. All of the Tipitaka are not true or useful, but all of the Dhamma is true and useful.

But none of it is unjust.

From the book "The Authenticity of the Early Buddhist Texts" by Ven. Sujato and Ven. Brahmali:

Both the EBTs (Early Buddhist Texts) and the later tradition, then, quite readily acknowledge that some discourses were not spoken by the Buddha. In some cases, such as the final verses of the Mahāparinibbāna Sutta, this could not have been otherwise, as the context is after the Buddha’s passing away. In other cases, however, such as the verses of the Lakkhaṇa Sutta, even though the Sutta features the Buddha himself, the commentary is still happy to acknowledge that the verse were added later. The fact, therefore, that in the majority of cases there is no acknowledgement of lateness tends to authenticate these text as having the historical Buddha as their origin.

Also from section 4.4.1 of the same book:

These episodes, and others, could easily have been edited out, but they were kept despite their awkwardness and their not fitting with later ideas. This indicates that the attitude towards preserving the EBT was very conservative.