There's a few Ellis Island records for Julia (sometimes with her husband) travelling from France to the US. By 1923 she's lost a few years - says she's aged 19 - and that age sticks through into later records
Added: Later records have her b c1892, and looking at the image of 1923 she's listed as age 30, so it's a dodgy transcrption that made her 19, but 30 is still younger than the age of Julia James on the censuses