I'm having a hard time deciding if casual, cavalier, nonchalant and indifferent could be used interchangeably in such contexts as the following:They (except the last one) are examples cited in Merriam Webster's either Unabridged Dictionary or Citations.
Cavalier
He has a cavalier disregard for the rights of others.
People are cavalier with facts, let alone with opinions.P. 9 JOURNALISM MADE SIMPLE David Wainwright W. H. Allen, London 072 W13j 1972
Nonchalant
She faced the crowd with the nonchalant ease of an experienced speaker.
The team may have been somewhat nonchalant at the beginning of the season, but they now know that they need to work hard.
Casual
were casual with their hogs and let them run through the peanut fields after harvest. P. 62 Roon Frost GOURMET Vol. XLI No. 4 April, 1981
Indifferent
How to remain indifferent to one's pleas both in times of trouble and in times of joy.