We need to know more about your team to give you detailed advice. There are lots of things that work against a 3-4-3 (even a strikerless one) but something that works great on paper but doesn't suit your players won't help much. If the screenshot further down that thread is an accurate representation of the formation/roles/duties, then that honestly seems like a really unbalanced tactic and there should be a number of ways around it.
Just in general though, remember a few things. Obviously the primary weakness of the 3-4-3 (or this, which is almost more of a 5-2-3) is down the flanks, where most standard 4-4-2 and 4-5-1 formations will outnumber it, so if you're playing a four-man defense, you should focus your buildup in wide areas, where you have the numerical advantage. Of course, with three true center backs, a crossing-oriented strategy isn't likely to have much success. You're more likely to get good results either from outside-in combination plays and pullbacks to players lurking outside the top of the box, so probably a good idea to have someone in that spot. Additionally, playing two forwards against three center backs is playing into your opponent's hands, because they have two man markers plus an additional defender. It's usually better to opt for one forward and a midfield three that allows you to outnumber their midfield two.
Can you maybe give a general description of what that 3-4-3 looks like in practice (where do they build their attacks/how, how do the various players behave without the ball, etc.) and some info about your team? That would really help us give you more specific advice. It's an interesting formation, but like I said, if that one screenshot is an accurate representation of the roles and duties, it seems unbalanced.