Why pray in Latin?
One of the perennial debates around the Office is what language you should use to pray in.
A debate on this topic appears to have been cut off elsewhere I can only assume in the interests of protecting perceived fiefdoms by virtue of leaving some misinformation in place. That's unfortunate, but I don't want to get into all of that here. Instead, some brief comments on the more important underlying issue around the use of Latin from my perspective.
1. Prayer in any language is better than none!
First, note that the most important thing is to pray - what language you use is a secondary issue. Prayer, as we all know, can take a wide variety of forms. We often use set forms (the Mass, the Divine Office, particular prayers) to help us. Sometimes the content might be what we are focusing on. Sometimes it is more the general intent behind the prayer.
In the case of the Divine Office, it is not necessary to be deeply conscious of the meaning of each word or phrase each time you say it (whether in your native language or some other). Far more important is the intent of praising and worshipping God.
2. When it comes to liturgical prayer, the important thing is to follow the approved rubrics
There are two broad types of prayer - liturgical (such as the Mass) and devotional (the rosary, meditation, etc). The Office can be said either as a devotion or as liturgy. If it is said devotionally, you have a fair amount of freedom as to how you say it. However, the Church strictly regulates the liturgy in order to protect its integrity. That includes the Divine Office (aka Liturgy of the Hours, etc).
In the Catholic Church, Latin is the official, normative language of the liturgy. Translations of the Latin have to be approved for liturgical use (not just study use) by the proper authorities.
3. Praying in Latin has advantages when it comes to liturgy
Since Vatican II, the use of the vernacular has been permissible for both the Mass and the Office. Sacrosanctum Concilium clearly intended the use of the vernacular to be rather limited, particularly when it came to the Office, and Popes from Paul VI onwards have stressed the desirability of preserving the tradition; instead, use of English has become the norm.
But use of the Latin is worth considering for a number of reasons. A number of religions use 'sacred languages' (Jews use Hebrew; Muslims, Arabic for example) in order to help create the sense of 'sacred space and time' - to help us focus on the sense of God's otherness to us. The use of 'hieratic' language reminds us that we are worshipping, not just chatting amongst friends. That's important in a world that is reluctant to kneel before its God. And in the Western Church, the Latin of the Vulgate achieved that position by virtue of being a neutral language that transcended individual cultures.
In the Western tradition, use of Latin as a universal language of the Church was regarded as a counter to the chaos of Babel, a practical means of continuing the gift of understanding engendered at that first Pentecost.
By using the Latin text, you are using the same words St Benedict would have sung in his monastery, and the same texts that generations of monks, nuns and oblates have used down the centuries until our own. You are entering into a tradition.
And by learning at least a smattering of Latin, you will find it easier to understand the great spiritual works of the West (including the Benedictine Rule) which assume the use of the Latin Vulgate as their starting point.
4. You don't have to be a great Latinist
The best way to learn a language is actually by immersion in it! Start using it, and with a bit of effort and few aids, you will gradually pick up a lot by osmosis.
The translation contained in the Monastic Diurnal is a very useful starting point for getting the sense of the text, even as you say the Latin. And there are some excellent resources around to help you gain a greater understanding of it, such as the very good Simplicissimus course specifically geared at helping people learn enough Latin to follow the Mass and Office.
You might also want to consider the suggestions outlined at my post on this subject in my how to learn the Office series.
5. Translation is one thing, understanding is another
It is also important to keep in mind that just understanding the literal meaning of a text is not enough. The Catechism of the Catholic Church (paras 115-119) stresses that Scriptural texts (including the psalms, chapter verses, many of the antiphons etc in the Office) has both a literal and a spiritual sense, and that the spiritual includes the allegorical, moral and anagogical meanings of the text. There is real value in looking at commentaries and treating the Office as a source of 'lectio' to penetrate its deeper meanings.
6. Do pray the Office!
Finally, by way of a summary, on an email list I was once a member of, a monk said that when they were novices they were taught about a hierarchy of 'attentions' for the Office, which I've adapted a little here. When thinking about the Office we should pay:
(1) Attention to the WORDS -- getting the rubrics right, so that we say the correct texts at the correct time; using the appropriate body postures; and saying or singing the words correctly;
(2) Attention to the SENSE -- focusing on the "what " we were saying, the translation of the words;
(3) Attention on GOD -- not worrying about words or sense but simply praying before the Divine Majesty.