I always find it super cool when people want to learn Swedish. It's not the most useful language to learn on account of Swedish speakers being a fairly small portion of the world's population, and most everyone here speaks English anyway. So the drive to learn Swedish is usually rooted in a genuine interest in some cultural or linguistic aspect, and that's amazing to me.

I've some notes for you.

Jag är så ~~lyckas~~ lycklig för ~~dig~~ din skull!

"Att lyckas" means "to succeed."

Lycklig means happy and shares roots with the word "lycka" meaning luck. A more common word for happy would be "glad" though in this context it doesn't make much sense. Lycklig to me has a much stronger feel to it. Like genuine joie de vivre.

While "dig" absolutely means "you", the phrase "happy for you" needs some tweaking to sound good in Swedish. "Din skull" is essentially "your sake", which I think could be interpreted as a bit passive-aggressive in English but that doesn't really translate to Swedish, unless you were to say it in a passive-aggressive manner.

~~Jag också vill att böra i Sverige in framtid, så detta är trevligt att läsa det!~~
Jag vill också bo i Sverige i framtiden, så det är trevligt att läsa detta!

"Böra" actually threw me for a loop because it sounds like a word, and it is, but it's archaic and seems to have a lot of meanings. The dictionary list is hella long, I definitely learned some new things here. In general though it seems to mean should/ought or "require."

I think the term "nice to read" being translated as "trevligt" sounds a bit strange in Swedish. I think I'd say "roligt att läsa/höra" (fun to read/hear). You could alternatively also replace "roligt" with "kul" and retain the meaning but sound a bit more casual.

~~Jag är ledsen om min svenska, jag lära också språket~~
Jag ber om ursäkt för min svenska, jag håller också på att lära mig språket.

"Jag är ledsen" would be interpreted very literally in Swedish as "I am sad", though because of the influence anglicisms has on Swedish I think this could potentially shift in the future. I've heard people use the expression "I'm afraid I can't..." in Swedish before, which is really funny when it's expressed to a person who isn't very enmeshed in the English language because they just go "??? What are you afraid of?"

"Hålla på att X" in this context means that you're actively doing something.

Jag håller på att laga middag.
I'm making dinner at the moment.

Jag håller på att göra klart för dagen.
I'm wrapping things up for the day.

Vad håller du på med? (I say this to my dog all the time) What are you up to?

Finally. Never apologise for your proficiency! Making mistakes is a natural part of learning, I'm sure I've made so many mistakes in this comment myself, and a bit of it is just my personal opinion/thoughts and I'm sure that people will disagree. Be proud of your progress instead! I think you're doing great, and the fact that you're even interested in learning our niche little language thrills me.