If you want short mantras, I suggest simple predication. I personally use a two part mantra which is simple and short "I am aware. I am dreaming." That's it. I'm not sure of the details of Latvian, but most languages have simple predicates as well as terms for dreaming and awareness. I imagine "I know. This is a dream." might also work with similar success. These could easily be strung together, and I do, but I felt like it was important that each simple predicate be sufficient on it's own on the off chance that my in-dream brain doesn't properly parse complex language properly. I've already found that tense and negatives don't work for me. "I will dream" for instance won't work. "I will not forget my intention" will also not work for the same reason. "I will recognize that I'm dreaming" will not work for several reasons, too complex and future tense. I have no idea if the same holds true for tense, negation, and complexity in other languages. That would be an interesting study.

As for whether or not you should try to LD, it couldn't hurt. The worst thing that might happen would be that you won't succeed that time. No big deal, there's always next time.