R language highlighting errors

I have noticed unexpected highlighting behavior for the R language. A few examples:

(1) The function, data.frame(), is highlighted with a purple ‘f’ and a gray ‘rame’ [‘data.’ is black]

(2) The variable name, Trt, receives different highlighting depending on the context. As part of a model formula, it is highlighted as purple ‘T’, gray ‘r’, and purple ‘t’. Inside of the data.frame function, it is highlighted as a purple ‘T’ and black ‘rt’.

(3) Most functions are not highlighted at all.

Thanks in advance for your help!

http://ww.wp.xz.cn/extend/plugins/crayon-syntax-highlighter/