If Portugal is dissatisfied, then a war between the two Iberian powers might break out. For Spain, a war could actually serve to train its army.
Such colonial disputes aren't significant enough to warrant forcible intervention from other great powers; at most, they would mediate. As long as the major powers do not intervene, Carlo has no fear in the Iberian conflict.
Not to mention a small Portugal. Even if two Portugals united, they would still not be able to rival Spain.
The gap between Portugal and Spain is not only in land area and population, but also in terms of comprehensive backwardness in economy, industry, population, and agriculture.
The land in Congo is extremely important to Carlo. It can not only develop agriculture and cultivate cash crops but also possesses extremely rich natural and mineral resources.
Congo is later known as the world's raw material repository, rich in various natural resources and many rare metals.
