The capitalization of the “era labels” is governed by the font choice you make. Timeline’s inventor made design choices for some font sets that using the CSS “text-transform: uppercase” made for the best presentation.
If you don’t want it capitalized, you can either choose different fonts or override the rule for
.tl-timeline .tl-timenav-slider .tl-timeaxis {
...
text-transform: uppercase;
...
}
A crude test suggests that these font sets don’t use the uppercase transformation:
abril-droidsans
amatic-andika
bevan-pontanosans
bitter-raleway
clicker-garamond
dancing-ledger
fjalla-average
georgia-helvetica
knightlab
lustria-lato
medula-lato
opensans-gentiumbook
playfair
playfair-faunaone
pt
roboto-megrim
rufina-sintony
ubuntu
but you should try them to be sure.
It’s difficult to point to the location in the Timeline Font CSS where this rule is implemented because of the minification, but the pre-compilation line that is the specific reason you’re seeing it in uppercase is
https://github.com/NUKnightLab/TimelineJS3/blob/master/source/less/fonts/font.pt.less#L32
I hope this helps. We will also be updating the Italian translation to use ‘a.C.’ as the prefix based on your information, in the next incremental update for TimelineJS.