Each went to great lengths to secure the exact same amount of land from the 2 nations they went to on Nesta's orders. Zaida never had the opportunity to negotiate with Rand when he was in control of Caemlyn, but she must have assumed Harine would come back with a Bargain with him and needed to get that land. The opportunity arose when Elayne needed the WFs to make Gateways and Zaida used it to create a strong Bargain getting the land she was set out to get as well as a powerful political alliance with Andor. Zaida could not make any moves with Elayne until Elayne had secured the Throne. She was sent to meet with Rand and got lucky when Elayne swung by to claim her Throne.

Nesta's bargain with Nynaeve and Elayne is the only reason Zaida was able to consider Traveling as an option, without Nesta ensuring that the AS would teach all of their Weaves to WFs Elayne would not have been able to use the WF to make gateways and Zaida would have been forced to look at something else to obtain the land she wanted in Andor.

But read the Bargain Harine made with Merana/Rafela ... it's clearly what Nesta sent them to accomplish.

The Path of Daggers
Chapter 27
The Bargain

"As you wish," Merana replied, inclining her head briefly. "Rafela and I have reached a bargain with the Sea Folk. The Bargain, they call it." The difference was clear to the ear. Hands lying still on gray-slashed green skirts, she drew a deep breath. She needed it. "Harine din Togara Two Winds, Wavemistress of Clan Shodein, speaking for Nesta din Reas Two Moons, Mistress of the Ships to the Atha’an Miere, and thus binding all the Atha’an Miere, has promised such ships as the Dragon Reborn needs, to sail when and where he needs them, for whatever purposes he requires." Merana did seem to grow a touch pontifical when there were no Wise Ones around; the Wise Ones did not allow it. "In return, Rafela and I, speaking for you, promised that the Dragon Reborn will not change any laws of the Atha’an Miere, as he has done among the... " For a moment, she faltered. "Forgive me. I am used to delivering agreements exactly as made. The word they used was ‘shorebound,’ but what they mean is what you have done in Tear and Cairhien." A question appeared in her eyes, and was gone. Perhaps she was wondering whether he had done the same in Illian. She had expressed relief that he had changed nothing in her native Andor.

"I suppose I can live with that," he muttered.

"Secondly," Rafela took up, folding plump hands at her waist, "you must give the Atha’an Miere land, a square one mile on a side, at every city on navigable water that you control now or come to control." She sounded less pompous than her companion, but only just. Nor did she sound entirely pleased with what she was saying. She was Tairen, after all, and few ports held a tighter control on their trade than Tear. "Within that area, the laws of the Atha’an Miere are to hold sway above any others. This agreement must also be made by the rulers of those ports so that... " It was her turn to falter, and her dark cheeks turned a trifle gray.

Harine's Bargain was designed to get as much land from as many nations as she could. It's clear Nesta and the First 12 sent Harine and Zaida with specific marching orders to gain land for trading enclaves well before they knew about Traveling.