I have noticed that both of these expressions tend to get replaced with English "no matter" and "from". The chêng is interesting in any case, having only half of the semantic range of the related Mandarin 從, in that it seems only to be used for expressions dealing with times, not those about places, which use tòa (or tī in other types of Hokkien) to indicate "from" a place. Interesting also that "from" seems to be used only to replace this chêng and not to replace tòa.#)"bô kóng sī hó-giáh ah-bô". I would be tempted to say "bô kúan" (= literally "don't pay attention to" = "no matter"). I feel that the "sī" is also optional. Not wrong, just equally as good without.
#) "chêng chá-khí kàu kā àm-mê•". I would leave out the "chêng", but in this case, it's not a correction to your usage, but just a comment on my own: I don't know how to say "*from*" in Hokkien, in this temporal sense, so I just leave it out.
The other one I noticed is "that's why....." I hear things like "That's why i bô lâi". I have no idea what the natural Penang Hokkien expression for this is, I would guess "In-ùi á-né-khóan...." four syllables versus two, perhaps that's why "that's why" wins out.
The other one I have commented on before was "before" which is not just lexical borrowings but also syntactic, as the Hokkien idiom elsewhere requires that its equivalent "í-chêng" is placed at the end of the clause. I am suspicious that "í-chêng" is in fact a Mandarinism, as (as far as I am aware) Penang Hokkien tends to prefer "not yet" or "about to" constructions using á-bōe + verb (maybe similar to Malay "belum" constructions?) or beh + verb + ê-sî.
Before wá khòaⁿ tióh i "Before I saw her" Before wá chhut khì ê-sî "Before I went out"
When you get all of these together in one phrase with other lexical borrowings the result ends up being more English than Hokkien:
"That's why before wá ū internet ê-sî...." but it isn't like that all the time.