
It's bad enough when game bugs out and you need to fix it by console, but when it happens to your campaign you've been playing for literally months, it can be really devastating. Conversion process is never perfect, so you're very likely to want to tweak some things with console commands or save game editing before and after export. I'd generally dislike ironman, but it's even more important not to play ironman for a few reasons:
Since Paradox games make it hard to avoid blobbing, you pretty much have to play with mods, severe self-imposed restrictions, switch countries every now and then, or otherwise do silly things or your second/third/fourth campaigns will be pretty boring. Possibly even chain multiple such games, like CK2 to EU4 to Vic2 to HoI4. Paradox Grand Strategy games cover very long time, and most people never even "finish" a single game of CK2, or EU4 - but it's possible to go the other extreme and play a "megacampaign" - start in one game, then convert to another, and keep playing.
CK2 To EU4 Converter - a modern fan-made utility for transferring CK2 to Europa Universalis IV.There's very little information about this wonderful thing, so after doing some research I decided to write it all up. CK2 To EU3 Converter - an older fan-made utility for transferring CK2 to Europa Universalis III. With Conclave DLC, the HRE becomes a single nation when the council is not empowered. If crown authority is absolute the HRE becomes a single nation instead. The seven largest vassals within the empire will become electors and the rest of the direct vassals will become normal princes. All vassals remain unless crown authority is Absolute. The Holy Roman Empire is implemented using EU4's HRE mechanics. A maximum of 4 EU vassals are created from a nation's largest vassals. The centralization law doesn't affect this. If any council laws are active, there will be some vassals. With council power abolished, the whole nation will stay independent. With Conclave enabled, this is tied to a realm's council power. With Minimal Crown Authority (Autonomous Vassals), kingdom-level vassals and duke-level vassals will become vassal states rather than integrated into the whole realm. Without the DLC though heresies will be only be converted if they have overtaken their parent religion in the game. With the Sons of Abraham DLC all heresies will also become unique religions. Hellenics also have their own unique religion. Zoroastrian nations continue as their EU4 equivalent unreformed Zunists become Zoroastrians. Most Unreformed Pagans become Animists, however CK2's Tengri nations will continue to be Tengri in EU4. Reformed Norse can also choose their own personal deities. Reformed Pagans all have their own unique religions in EU4. Economic view in CK2 gives a preview of the probable development in the export. Provinces convert to a dynamic amount of development, depending on total income generated by holdings in corresponding provinces in CK2 (as of CK2 2.7.2). With Sunset Invasion active, The Inca and Aztec empires will have the High American tech group, as well as large empires in the New World. Unique national ideas for Aztec, Hashashin, Inca, Israel, Jomsvikings, Karlings, Knights Templar, and the Roman Empire. It is recommended to pick a nation, start a game, and immediately save and restart back to the screen that lets you select a nation in order to have the actual generated ideas appear). Nations without equivalents gain randomly generated ideas (though at the moment there appears to be a glitch where generic national ideas appear on the launch screen, as it seems ideas are only generated upon first launch of a game using the generated mod. Nations that have an equivalent in EU4 gain their national ideas. Flags are carried over for the nations as well for CK2 nations that have no equivalent in EU4. Dynamic country tags are created for CK2 realms without equivalents in the base EU4 game. EU4 TO VICTORIA 2 CONVERTER MOD
A CK2 save (from any year) is turned into a mod for the EU4 start-date of 1444, allowing the player to continue on to 1821.