Nobody can know precisely whether you will be able to enter or not.
What we can tell you is that in most countries, even after a ban has ended, authorities will consider your case with a lot of suspicion. If you previously overstayed, you are deemed not to be trustworthy, so if they match you up with that previous issue, at the very least you will be grilled a bit more than usual.
The possible outcomes are:
- They don't match you with that previous problem (because they don't have a way to look it up easily), and it's as if you were any other regular visitor
- They know about the problem but don't care and think this is all water under the bridge
- They know about the problem, ask a lot of questions, possibly send you to secondary, but let you enter in the end
- They know about the problem and consider you are not trustworthy and refuse entry
What the probabilities of each of those is nearly impossible to guess. The fact you are using a different passport may make the first more probable than in other cases (e.g. with a big stamp in your passport), but it all depends on what records they have and how they can look them up (e.g. via biometrics).
In any case, if you are asked any questions, do not lie. Do not provide more information than they ask for, but do not omit anything they ask for. If they ask about a previous stay or overstay, do not try to pretend you're not that same person. The fact that you have a different passport from a different country does not make you a different person.
The usual advice in this kind of situation is to tell you to request a visa beforehand. Better to have a rejection while you're at home than to undergo the gruelling process of being sent to secondary, being refused entry, put in detention and sent back home.
But if you already have a law firm on your case, the best option by far is to ask them. They will have far more experience and better advice than we can give.