Over here, I will give a more detailed explain about what I have done.

For popularity, first I completed the popularity protection system, just like in the real world, it is very difficult to completely end the life of a party, so if the popularity of the opposition party drops too low, this mechanic will give it extra support to make it maintain a lower balance rather than disappear completely.
Second, if you complain that popularity changes too fast compared to reality, then there is a "political tradition" system. Some countries with relatively independent worldviews will add different popularity drift based on their initial support rates of each political parties. For example, a Countries with 43% pro-Western support, then get +0.04 Western drift on start, and countries with 68% Emerging support get +0.07 emerging drift (remember, this will be set in stone once started).
Third, some countries have no independent worldview, but they will be greatly influenced by some interesting countries, like Thailand in Southeast Asia, Egypt in Arab world, Ethiopia in Sub-Saharan Africa, countries in this regions will be seriously impacted by these countries, so remember, if you want to make friends with these regions, try to influence SIA/EGY/ETH first.