Converting Code from other Platforms

I am using this from another platform to make a Roman Numeral Face .
Some may Recognise the Syntax.

$#BLN#==1?I:$$#BLN#==2?II:$$#BLN#==3?III:$

How ever what I thought might be the equivalent for WFS dose not work in text box of a text layer .

([BATT_PER]==1?I:)([BATT_PER]==2?II:)([BATT_PER]==3?III:)

It seems like the Conditional will only work with numbers.

Any Help will be Appreciated .
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Oh well this might be useful to someone .

I took a little break and remembered some of my Old Basic .

([BATT_PER]==98?"XCVIII":"")([BATT_PER]==99?"XCIX":"")([BATT_PER]==100?"C":"")

Sorted now .