Scientifical?

Scientifical is not a word (maybe a scientist out there will try and correct me). It should be scientific. Scientific is an adjective.
To change adjectives that end in -IC, we often (though not always) add -ALLY to make it into an adverb.

Then how come biologic and biological have the same definition? Is this another one of those rules where "we don't have a reason for that, it just is"?.

If politics refer to the applied methods of policies, why doesn't scientifics refer to the applied methods of science?

Political is relating to, or dealing with the structure or affairs of government.

Why doesn't Sci

Don't worry. It's confusing to all students learning English at some time or other.
I just created another post that might help show you that English is full of exceptions.
As you say many things are because "it just is".

English is hard to learn because ...

Excellent article Woodward! Even though it was knee slapping hilarious, it does not fully answer my question. It did, however, open my mind to the fact that numerous exceptions exist. But, why are words like “scientifical” and “forensical” improper words? While political and economical are fine? Is this because the use of “scientific” and “forensic” are incorrect?

Like I said (and you said) before sometimes it just is that way without any logical explanation. The only explanation I can give is that it doesn't sound right. I know that it isn't a good one but honestly I don't know why else. Maybe someone else could help out.
Are these words just exceptions that should be accepted as is or is there some logical (or illogical) explanation?

Bestest?

I feel like when the words ending in al such as economical and logical are used in that tense it’s only to show that it’s an ongoing thing, for example an economic depression is only temporary but an astrological event might be long lasting in terms of how humans look at time. Not sure on that at all but I could be on to something.