Translation:He does be excited when he goes to Germany.
I dont have a problem with "do be", I have a problem with the fact that it is used inconsistently. there is a phrase in the travel section that uses the word "Bionn" however it accepts the use of the word "is/I am" (infact I think it even marks one wrong for saying "do be").
Here are two articles from the Irish Times that include direct quotations of ordinary people saying "I do be" and "She does be". This construction is not often seen in written English, but it is absolutely a normal part of the vernacular for many Irish people. It is worth nothing that both of these examples reflect urban speech, not rural speech. This construction is not restricted to rural areas.
Further up the street, florist Dee Curry was parked in a loading bay making one of her many deliveries around the city: “Most of the time, I do be dreading trying to get parking,” she said.
She does be sobbing going home from visits and it’s horrible to be looking at your child like that. https://www.irishtimes.com/life-and-style/health-family/parenting/the-mothers-spending-christmas-in-prison-1.3331306?mode=amp
"Does be" is said, but so is the gramatically correct version "is" which is used by vastly more people worldwide, and in ireland, rather than examples above which are closely linked to a particular socio-economic group. I live in Ireland, accept we have variations of saying things but this is too far from the daily reality of most English speaking Irish people to be the sole accepted answer.
If the course was trying to teach English to Irish speakers there might be a point to your objection, but the course is trying to teach Irish to English speakers, and English speakers need help to understand and reinforce the difference between tá and bíonn, a concept that does not come naturally to most English speakers.
It's one thing for English speakers who aren't from Ireland to complain that they can't understand what "does be" really means, because the concept is entirely absent from their worldview, but for an Irish person who actually comprehends the concept of "does be" and how it is used, to fall back on socio-economic snobbery as a reason for extinguishing the distinction between bíonn and tá when translating from Irish to English is, at best, unfortunate.
The computer can't tell whether someone who enters "He is excited when he goes to Germany" understands the difference between bíonn and tá, so it requires "does be" to ensure that the difference is at least acknowledged.
Again, I don't expect the English translation to be that of a "dialect" of English, but standard English, which this is not. It is nice that Duo has the translation to English done by an Irish speaker, but it would also be nice to have the final translations run by a native English speaker who would definitely say he does be is not standard, as opposed to dialectical English. I'm trying to learn Irish, not a dialect of English that appears, from the comments, to be problematic for British, American and even some Irish speakers, who also agree it isn't correct
The Americans are even more confused by it than you are.
The people who have no problem with it (because it is a perfectly valid construction in their English) are the Irish people who wrote the exercise, and the Irish people (from all parts of the country, urban and rural, North, South, East and West) who either use this construction, or who encounter it being used by other Irish people.