Ismytranslationcorrect? - 社會議題

請問以下這段文字我這樣翻譯正確嗎?
原文:
Freyre and Tannenbaum have rightly argued that the lack of certain
traditions in North America --- such as a Roman conception of slavery
and a Roman Catholic emphasis on equality --- explains why the
treatment of Black slaves was more severe there than in the Spanish and
Portuguese colonies of South America. But this cannot be the whole
explanation since it is merely negative, based only on a lack of
something. A more compelling explanation is that the early and
sometimes extreme racial discrimination in the English colonies helped
determine the particular nature of the slavery that followed
中文翻譯:
Freyre 和 Tannenbaum 對於北美洲的非洲奴隸(黑奴)的待遇
比在南美洲的西班牙和葡萄牙的殖民地的非洲奴隸更苛刻
的原因提出了論證, 認為一些特定的傳統的缺乏 --- 例如羅馬的
奴隸概念和羅馬天主教對平等的重視 --- 可以解釋這個現象.
但是這並不能成為一個完整的解釋, 因為它只有負面,
僅僅建立在某個東西的缺乏.
一個更令人信服的解釋是, 英國殖民地的早期和在某些時期的
極端的種族歧視影響了後續的奴隸制度的特定本質.
1. 其中有沒有翻譯不正確的地方?
2. A more compelling explanation is that the early and
sometimes extreme racial discrimination in the English colonies helped
determine the particular nature of the slavery that followed
最後這一句話有沒有更適當的翻譯?
the salvery that followed 是否就是指 "後續的奴隸制度"?
3. Freyre and Tannenbaum have rightly argued......
其中的 rightly 可否視為只是加強語氣, 並無任何意義?