You sound to have a very complicated taxing situation, if it's too complex it's good to give the job to some expert even tough you must be careful because if he makes mistakes, it's your balls going in troubles not his ones, then state starts harassing you and you are doomed
You said that one was 3500$ cheaper, my god how much you pay a full year, that's insane!
Honestly I can't compare your situation there with the equivalent here, here it works like this, if your income is already taxed at source, then you are fine, no need to declare anything (examples lottery, betting, work employer wage), otherwise you must declare it and calculate taxes to pay on your own and pay them (example cash out from crypto, house rents)
Actually i just have my employer wage so I wouldn't even have to do any declaration, however I do it anyway because you can get some money back from medicines, visits, kid stuff... I just do it myself because in my situation it's fairly easy, even if I had 1 own living house I wouldn't have to pay anything on it
As for crypto I won't declare them for now, it too little anyways now