I am confused as to why some regions that were not historically under Roman rule, such as Ireland, Scotland, and a large part of Germany, have been converted to Sol Invictus? also, is there a reason why Ireland has English Ideas and an English Culture ruler?

I debated on those issues myself but I finally went down the path of, if the new Sol Invictus religion (which would have likely had influence from Christianity and its proselytizing nature) had spread to the Roman world, then just like in our own time it may have spread beyond the Roman controlled world just like Christianity had. A reason why many of the Germanic tribes converted to Christianity was that it was also part of the infrastructure and culture of the previously Roman regions they now controlled. Upon their Conversion to Christianity it would spread further into Germania in the OTL which if in this world they still captured those Roman territories (albeit later) they could have converted to the new religion or adapted to some of it for the same reasons as Christianity and thus spreading to Germania too. Its why I added Germanic deities to simulate cultural adaption and/or inclusion of their gods into the faith, while I also applied that same logic to Scotland and Ireland being Sol Invictus as well (Again this may not be the most accurate approach). As for the English Ideas, that is an issue which happened when I was converting from CK2 a while back and Ireland wouldn't have its unique unit models because it was renamed to Eire, and only it having English culture gave it its unique model, and when I published this mod I focused mainly on the Mediterranean, unfortunately neglecting the Emerald Isle. Let me know if you want and I can change its culture and give it its own ideas in an update.

I see. Perhaps you could make it so that Ireland could be a last bastion for the Celtic religion in a similar way that Saxony, Denmark, Sjaelland, and the other Norse countries are the last bastions of their religion. as for the English Ireland, would it be easier to leave it as Eire and give Eire the Irish unit models?

I still haven't mastered unit model modding but I think I can rename the country and give it Irish culture instead with the model still working. And later on I can add a Celtic/Druidic faith for them and possibly Scotland

Well I did add a new Celtic Pagan Faith for Ireland and I did fix their English culture issue

thanks! I am already trying it out.

Why is Estonia Germanic? Also how did Andalusia and Israel come to be in the first place?

Well, Estonia is Germanic because it is controlled by the Jomvikings which is the Norse holy order in CK2 which I put them their originally cause I wanted a place to for them since they had a set of unique ideas for EU4, but they are vikings and thus the Slavic areas are still lands they would raid and occupy not too dissimilar from the Rus. Andalusia exists as even in this reality Rome was dealing with a lot of factors, such as the Lombards and Bulgars, and the rise of the Arabs in the 7th century would likely have still been shocking, if Islam came to exist in this reality. So Islam would most likely spread into the Levant, North Africa and possibly even into Spain, still in this reality, due to the Romans being completely surprised, which is ultimately why I chose to have Andalusia exist. Now for Israel, Julian II in our timeline wanted to have positive relations with the Jewish people and even wanted to rebuild their Solomon temple, if mostly as an insult to the Christians, so if we say he lives longer then he would likely achieve those former things. If that is the case many Jewish people might return to Israel since it has become much safer for them to do so. I also imagine as the centuries continued then their would have been battles between Islam and the followers of Sol, so not only could Jews have helped in these battles but could have been given and/or left an independent state for a variety of reasons such as acting as a buffer state to Arabia. Ultimately, like I said in the description these might not be the most realistic nations which would exist but I wanted to see them there and its not like their is no logic for their placement at all either.