When I read science papers in French or in English, sometimes, I want to know the translations of some words in Esperanto. However, after some research on the Internet, I found nothing.
Should I translate them and start use them, even though I have no qualifications to do so?
Yes, you translate and start using it. You should mention somewhere in your text what your translations are, unless they are evident.
The real problem is how to translate. In Esperanto you don't (you shouldn't) translate words, but roots. That's the way the language works and that's how we keep it as simple as possible. Roots allow for related words to be built.
There is also a rule that allows for the semi-automatic addition of roots. Rule 15 of the Fundamenta Gramatiko states: "The so-called „foreign” words, i. e. words which the greater number of languages have derived from the same source, undergo no change in the international language, beyond conforming to its system of orthography. [...]"
Let's say you have to translate for the first time "email" and "spam"; you could go for:
emajl-o and spam-o
Those two are actual translations, found in dictionaries (you could have come up with them in our imaginary situation). You would then add a new root and a new meaning to an existing one. In the case of spam- it could even be a good idea if you then reuse that root for other situations. A new root should be productive, if it mimics the original language, only makes sense with -o and works for a single concept, it looks like a lazy translation, or a word translation. I would consider it part of root polution.
You could also use:
ret-mesaĝ-o and trud-mesaĝ-o
And leave the roots alone, while using one of the main features of an agglutinative language.
In the end you decide how to translate the terms, whether you want to be them readily recognizable by specialists or by Esperanto speakers.
My advice is to try to avoid adding new roots but if you do add one (sometimes you just have to), do it so that the semantic field of the new root allows you to use other Esperanto elements around it to make the root productive and allow for other related concepts to be described right away.
It also depends on your public. What would you rather read, as an Esperanto speaker instead of spondylolisthesis:
spondilolistezo aŭ vertebra misŝovo? (from this question).
spondilolistezo could prevent any ambiguity of a logical specifiying translation. When you have to live with other languages too, my advise would be to use at least once the neologism (spondilolistezo), and then revert to an easier translation (vertebra misŝovo - when you are certain of its apptness).