Have you understood the construction “superandi causā” ? It’s not clear from your translation whether you have or not. Was that what led you to ask for help or was it something else?
Also, your translation of the main clause does not communicate to me that you understand how the Latin actually works. Did you realize that Romānīs is the dative complement with placuit, that imperāre is active (not passive as you have it) and that Scipiōnī is the indirect object of imperāre?
Just for the sake of learning, what would be the correct translation to that sentence, seneca? And doesn’t superandi causa mean for the reason of overcoming? So isn’t his translation of that more idiomatic to English than to say ‘for the reason of overcoming?’
My best translation of that sentence would:
It pleased the Romans to order Scipio to go across into Africa to overcome Hannibal.
Posts have contexts. I understood the OP to be in an early stage of his Latin studies and not to be a native speaker. I asked whether he had understood the latin construction because it wasn’t clear from his translation. The fact that he had turned the active to the passive in the first part of the sentence fuelled my doubts.
Translation in terms of getting the “right” answer is of secondary importance to understanding how a sentence is constructed in Latin. I suppose with a more advanced student I would expect them to ask about how a construction works and then as a separate question if necessary how that would be best be translated idiomatically. Less advanced students conflate these questions and it’s not clear where the actual difficulty lies. But it’s usually with the Latin.
For some reason the OP created another parallel thread on this question. Aetos helpfully posted this which might inform your translation: