There would be almost zero change.
Liberia in the mid-19th century consisted of a few Americo-Liberian settlements along the coast which were thoroughly segregated from the indigenous population that filled the remainder of the country. The Americo-Liberians were generally Christian, English-speaking, and sought to recreate the American social and political system with themselves in the highest caste. The natives generally kept to indigenous religions and, to a lesser extent, Islam, and sought to either avoid contact with the first group or expel them entirely. The third group, the Congoes, consisted of recently-freed Congolese from Central Africa who generally identified with the Americo-Liberians.
The natives at this time numbered perhaps 500,000 (exact numbers are difficult to estimate), and in all likelihood they wouldn't even care who claims the territory since the level of actual territorial control is near zero. The Americo-Liberians and Congoes together at this time numbered almost certainly fewer than 10,000, and chartering a ship across the Atlantic in this era to transport even a tiny fraction of them would be an extreme expenditure of time, money, and resources; it's unlikely that more than a few hundred could feasibly even make the journey unless someone very wealthy wanted to bankroll their transportation. The African-American population of the US at this time period is more than 4 million, so I seriously doubt the addition of a few hundred of these would have much effect on anything at all.