Why is "the test is failed" acceptable?

Step 'master>Build Project' is failed.

It sounds like "failed" here is acting as an adjective, in the same way you could say: "Step 4 is required." or "Step 4 is completed".

Technically this is correct - participles can be used as adjectives. However, the use of "failed" in that manner sounds awkward to me and I can't put my finger on why exactly. It might be because "failed" is not usually thought of as a static state, but more as an action.

If a required re-certification test is failed...

This one and the others all sound like the verb "failed" is being used in passive voice. They could all be rewritten into active voice like: "If the technician fails a re-certification test..." or "If the test subject detects the odor, the test fails..."

In many styles of writing, active voice is preferred over passive voice for clarity and easier reading. However, in other styles of writing (particularly technical/legalese, which it sounds like you're quoting from), the more stilted sound of passive voice is more common - and perhaps even preferred. Either way, it is correct.

Without more complete sentence examples it's hard to be sure about this, but in the IT environment I work in, "Failed" can be either a past-tense verb or an adjective describing something in a state of failure.

In the former sense, "the test is failed" is incorrect. In the latter sense, "the build is (in a) failed (state) is acceptable.

There are at least two kinds of tests. In standardized tests, you are dealing with fairly well known outcomes and the test is to see if a given entity meets those standards.

The driving test is failed by many people every day.

The test isn't a failure, it is an accepted standard that many takers cannot meet (at least yet).

In experiments, a standard or goal, often not fully known or established, is postulated. The experiment (or test) is conducted. If the outcome is not what is expected, the test has failed, not necessarily the tester or test taker.

For the experimental vaccine, the test has failed to show any beneficial results.

Build seems a bit more complex in that it is jargon within a particular field and might be better answered by experts in that field.

SUPPLEMENT The following is in response to the original poster's comment below.

In the test is failed usage discussed above, the logical subject of the discussion is the test taker.

John fails the driving test

The driving test is failed by John

The second sentence is a passive construction that moves the logical subject (John) into a prepositional phrase. While test is the grammatical subject, it is still not the logical subject, but the logical object of the sentence.

In the second example, the test itself is the logical subject of the discussion.

The test (e.g. the experiment) has failed to yield results.

This is an active voice and the test is the grammatical and logical subject of the sentence. It could also be said in the simple past tense as

The test failed to yield results