Here's an alternate translation in case you want a second opinion on some of the phrasing:
いきょうとから せいちだっかんの
[せいせん]のなのもとに、スカンバ
きょうこくは ヘルクルセーダーズ
えんせいをかいしした。
The powerful country of Skanva
launched a campaign of "Hell Crusaders"
to reclaim the holy land from heretics.
They called it a "Holy War".
えんせいぐんは せいちアンガル
せんりょうにせいこうし、そのけっか、
えんせいぐん しれいかん ぼうてい
カルワリオの こうりょうこっかが
けんせつされた。
The expedition succeeded in capturing
the sacred land of Angar,
resulting in the establishment of
a bleak, desolate nation by
Calvario, the emporer's guard and
commander of the expedition forces.
しかし、ぼうていカルワリオのもくてきは
りょうしゅになることでも ぶくんをたてる
ことでもなかった。 かれの もくてきとは、
でんせつの 8つのせいせきをさがしだし、
[むてきのちから]をていにいれ、せかいの
おうとして くんりんすることにあったのだ。
However, Calvario's aim was neither
to rule over a territory nor to become a distinguished
military leader.
His goal was to discover legendary Eight Sacred Stones,
giving him the "unrivaled power" to reign as king over the
entire world.
ぼうていカルワリオは せいせきを
さがしだすために、 むほうのかぎりを
つくしていた。
だが、 ここに はんヘルクルセーダーズの
えいゆう しししんおうナラシンハが
あらわれたのだ。
Calvario was carrying out every manner of lawless
deed in order to find the stones.
It was then that there appeared
a hero who stood against the Hell Crusaders
-- Narshinha the Lionhearted.
NOTES: I also had trouble with the word ぼうてい. I settled on 防帝, which would mean "protector of the emporer", but I think it might also be 望帝, which would mean "one who aspires to be emporer/king". It's possible that it's being used as a title of praise, similar to "-- the Lionhearted" or "-- the Brave". At any rate, you'll need to use some creativity here.
HTH