Is it legal to bribe a potential plaintiff and provoke him/her to file a lawsuit against someone if he/she wouldn't want to do it without a bribe and persuasion? How such situations are treated in modern civilized countries?

So you did something and it could result in a lawsuit. The person you did it to wasn't going to sue until someone else offered them an incentive to pursue the case. Is this somewhat accurate?

I'm not sure bribery applies. A bribe has to go to a person in a position of authority or trust in order to sway their judgement. There are several such people involved in legal actions, but the plaintiff isn't one of them.

And there's nothing illegal about persuasion. Unless the lawsuit is trivial and might get thrown out anyway, I don't believe you could press charges against someone who encouraged another to seek legal action.

This sounds like someone who doesn't like you found a way to hurt you by "hiring" a third party. I'm not a legal expert, and I know less about Canadian law than US, but I don't think this is illegal. The persuader can say the "bribe" was to cover expenses, or it was a loan, or it was unrelated to the lawsuit.