歌(です)
良い歌を聞いこえた。(だから)その歌につういて話したい。翻訳してみたい。歌い手は彼女性です。(better: 女性。or 女性だ。)
*It's better not to mix up the formal and informal form, however, from here, you wrote in the formal way, so I won't correct about the form.
1. とてもうれしかったよ
(I was very happy); しかし [-かった-] の発音は(-katta-)です。でもこの歌ではその音は(-kAAta-) とか (-kaWAta) とか発音されています。変だな。そしてなぜここには「うれしかった」 と書かれていまですか。「嬉しかった」 と漢字で書いた方がもっと良いですか(or 良いのではないですか)。
*You can choose both, writing in hiragana or kanji, it depends on one's liking. Sometimes writing in hiragana seems "soft".
2. 君が笑いかけてた (You + laugh+kaketeta). I dont know kanji of Kaketeta (but its past form),i can suppose here same like 笑い続けた (laughed and continue laughing)
*We don't generally use kanji for this かけてた(the infinitive is かける), and it means the action of "laughing" is toward someone, "laugh to me" or "laugh to other person".
3. すべてを溶かす微笑みで (all+melt+laugh/smile) Hm, what the difference with [笑いと微笑みと笑顔] 2+3 seems must be together - You are laughing with smile, that can melt(kindle) all(everything).
*Your translation is very good. Basically 笑い = laugh、微笑み = smile、笑顔 = smiling face
4. 春はまだ遠くて (spring still far away) But I dont know form 遠くて, 遠い (tooi) - distant/far... mada -kute forms shiranakatta :)
*遠くて comes from the adjective 遠い、"the -TE form" of 遠い. (You can find the explanation with "Japanese adjective -te form".
5. つめたい土の中で (inside the cold earth/soil)
6. 芽吹く瞬間を待ってたんだ (In song 瞬間をの代わりには「とき」と読みまです。) Is it my text wrong or just it can read shunkan like toki too? (grow+time+waited) 5+6 seems must be together too. Now I can suppose united sense 5and6= Inside the cold earth I waited for a time to grow(rise).
Sometimes, especially in poem (lyric), kanji can be read irregularly. All depends on the author. For names of the people and places, too.
そこの歌を翻訳していする時はとてもうれしかった。(I would say: この歌を翻訳している間は楽しかった or この歌を翻訳できてうれしい。
Good job! Please keep up. I hope this helps you.
