From the KPMG page on Romania1. Romania has a worldwide taxation system that means that they will tax on all your income no matter if you lived there or not.
2. As long as you are a tax resident in Romania, and you are for sure as you did not change that, you have to declare and pay tax there.
Worst case scenario: some of the financial institutions you used reported you to Romania, the tax authority will calculate the tax you owe, all the social security contributions, will add a huge % as an interest rate. If you have any bank accounts or properties in Romania they will seize them.
Unlikely, but possible and pretty easy, they can go after your bank accounts within the EU especially if they know where they are.
If you have accounts outside the EU the chances they will be able to seize them is 0.1% and if we are not talking of hundreds of thousands of euros they will not even bother.
Eventually all your debts will be prescribed and you will be good as new.
Best case scenario: Nobody reported you so the fiscal authority thinks you either work somewhere else and forgot to change your fiscal residency or you just do not work at all. If they do not see any financial movement on your accounts or if nobody reports you they can not do anything about it.
You may want for example to obtain a residence in Portugal, register as a non dom (NHR) tax resident so you will not pay tax on foreign sourced income for 10 years.
Once registered, with the Portuguese tax certificate you can cancel your Romanian tax residence.
As a freelancer with the NHR residency you might be taxed in Portugal but you are for example exempt to pay tax on foreign dividends. So you can easily open a company in a lower tax jurisdiction (but not a tax heaven because then Portugal will tax you), get the dividends from there and pay 0% in Portugal.
Exempt income includes the following (however certain conditions must be met):
employment income derived from non-Romanian employers in respect of work done outside Romania, unless this income is paid by or on behalf of a Romanian employer