Hello. I am a foreigner and I don't speak or write Taiwanese Minnan.
We were training a system regarding transcription of this written language to phonetic IPA.

The quality of data was bad because chinese text wasn't exactly what was spoken.

example 1:

chinese text is too big:

一面抹壁雙面光。
用抹刀抹牆壁，不但牆壁光滑，連抹刀也光滑。形容人很會做人，雙方面都能討好。
Tsi̍t-bīn buah-piah siang-bīn kng.

example 2:

chinese text too big/ not exactly what spoken:
七除八扣
計算時一再折扣，自總數中盡量減除。
tshit-tû-peh-khàu

Regarding column 1 there are also probably mistakes:
宣布命令 in minnan roman -> suan1-poo3 bing7-ling7
But not sure if they speak like this in Taiwan because I never visited.

Hope that you will understand my concern and hope that you will understand because It's difficult for me to explain it.

Thank you.