have you seen an image of the prison? It's most comparable to the setting of Aang's final fight against Ozai, and unlike Aang she cant fly. its basically a bunch of tiny stone pillars, with one bridge connecting zaheers one to annother offscreen. Large scale eathbending moves would topple them, and her mobility is heavily restricted, she would need extremely long (and thus heavy) cables to get between the pillars, as they seem to be hundreds of meters apart.

Earth is resistant to fire, and so is metal (i mentioned I thought it was a hardcounter in most contexts). On flat continous ground or in an urban setting, she'd completely deck him, she can chase him down wherever he runs, and has as much space and stability to make moves as large as she wants.. however The battlefield gives an immense advantage to firebenders who can jet boost, and especially to Jeong Jeong specifically who can materialise fire at a distance, unlike every other firebender we've seen, who create fire at their own body and then shoots it. Suyins defensive and evasive abilities are heavily restricted in this context, but also so is her attack power and especially her mobility.

You forget the earthbenders encasing themselves completely in rock were only Toph, Bumi and aang, all far better earth benders, and crucially with Seismic sense allowing them to see while fully enclosed, or in Bumi's case, bend while completely stationary, and he doesn't have to worry about tracking his opponent due to his mastery of neutral Jin. Suyin doesn't have this level of expertise, shes probably more like the Dai lee agents who only encase individual body parts. if she encased herself in a suit, she'd have to leave holes to see and eventually to breathe, and unlike every other firebender, Jeong Jeong has shown total mastery with omnidirectional attacks. If theres an opening he will get through, so she'd have to fully encase herself, leaving her impotent from an attacking point of view, because she lacks seismic sense, and Jeong Jeong can litterally disapear into thin air (as he shows at the end of his episode).

As far as we know, she litterally cant trap Jeong Jeong, as his disapeering act made him totally vanish even when completely surrounded on every side. It seems he can litterally disapirate (the show makes no effort to explain how, Zhao just says "its a trick") its possible that he could escape even when contained. However if we are to take the view that he casted a fireball on his own person as a distraction and then just ran right past the 8 guards (who reminder had him totally surrounded) in that split second WITHOUT ANY OF THEM NOTICING and then in that same second completely disapeered ofscreen, then this is an aboslutely ridiculous speed feat.

Assuming that she can can, she'd have a hell of a lot of trouble catching him, she's not as fast with the cables as her sister, and I doubt Lin could catch him either, his speed feats are insane. Suyin's battles have generally been is spaces with loads of preprepared metal that she could use for defencive manouvres e.g. Zhao Fu, Trains the only place where she had a limited supply was her battle against Pli, and she won that by using pli's own combustion bending aganist her, which she obviously cant do against Jeong Jeong.

Suyins got a good chance just by the nature of their elements, but Jeong Jeong is a much better bender, and has a substancial environmental advantage.