The name Trump is transliterated into Greek as Τραμπ. This is a fairly straightforward transliteration, but the reverse direction is surprisingly ambiguous. I found one news article where Google Translate translates Τραμπ back into English three different ways in the same article, none of them correct:

US President Donald Trub

President Trabble

President Trabid

What's going on here? There are two sources of ambiguity in the transliteration that keeps it from roundtripping successfully.

Ambiguous vowel

The first source of ambiguity is the vowel. The four consonants in Trump are transliterated to pretty straightforward equivalents. The vowel however becomes an 'α' (alpha), because Greek phonology doesn't have an 'uh' sound, and an 'ah' is the closest approximation. (This is a common feature of Greek accents in English for the same reason, with the word 'but' pronounced roughly 'baht'.)

Of course, 'α' can also be used to transliterate words where the sound was originally an 'ah' in English. Therefore when going back to English, there's ambiguity as to which sound it originally represented.

Ambiguous consonant cluster

The second source of ambiguity is the final consonant cluster, 'mp'. In most contexts, m↔μ and p↔π are unproblematically equivalent. However, when combined into the cluster 'μπ', there are three possible pronunciations: 'mp', 'mb', or 'b'.

In many cases, the choice is allophonic; which of the three is realized depends on the surrounding phonemes and on how quickly or formally someone is speaking. But Greek has no letter that's equivalent to English 'b', so 'μπ' can also be used as a digraph for plain 'b', especially in loanwords and transliterations. For example, the name Robert becomes Ρόμπερτ.

Combined ambiguity plus autocorrect

Combining these two sources of ambiguity, there are six reasonable guesses for how you'd transliterate Τραμπ back into English, given no additional information:

Trab

Tramb

Tramp

Trub

Trumb

Trump

You'd think that with this particular name, Google's corpus would have additional information, but apparently not. Let's go back to the three machine translations of Τραμπ at the start of this post: Trub, Trabble, Trabid. Here's a guess as to what happened.

First, of the six possibilities, Trab and Trub might be preferred because word-final '-μπ' occurs most often in loanwords and transliterations, where it was used to represent a word-final '-b' in the source language. Note that I have not checked this guess against any kind of corpus. But if true, that would explain Trub.

Trabble and Trabid then seem likely to be spurious spelling autocorrections of Trab. Trabble is the name of an app, and Trabid is an enzyme. I've noticed before that some of the stranger Google Translate errors are due to a spurious spelling correction having happened on either the source or destination side. When you combine that with the other sources of ambiguity in language, you can end up with results pretty far away from where you started.