Translate office to Tagalog and you get opisina. There is no doubt that most Filipinos will understand this word (even the non-Tagalog speakers). Yet the Tagalog word for office is tanggapan, or literally, "place that receives". Question is, when a client asks for a "Filipino" translation, which do you use?
Note that "Filipino" is a political designation that is based largely on Tagalog. Hence, translators, when requested to translate in Filipino will use either "opisina" or "tanggapan" not because they clearly know the difference between Tagalog and Filipino, but because each word is indeed Filipino and Tagalog.
The style of the document
may guide the Tagalog words to be used.
When adapting a word into either Filipino or Tagalog, some translators simply erase one, whichever is being used, and use an alternative from the dictionary. This challenges the evaluators. They may then opt to check using the rule of consistency, so that the level or style of language stays the same all throughout the document.
Office furniture will definitely be mga kasangkapan sa opisina. Yetkagamitan for furniture isn't wrong. The rough literal back translation is "things in use". The short cut mga gamit sa opisina favoring "gamit" over "kagamitan" is a variant of this translation. The internal context validates this choice since it means "things you use in the office, including furniture (and especially furniture)."
For consistency, if the document uses "tanggapan" for office, then it must use "kasangkapan" for furniture. This keeps the language consistently at a "deeper" level than when you use "opisina" and "kagamitan" combined. But anybody can contest this. One may insist that "kagamitan" and "kasangkapan" for furniture are interchangeable, and only the sensitive ear will notice a nuance.
Moreover, this rule isn't in any Balarila or Filipino or Tagalog grammar book or manual. This rule applies when writing in English: keep the voice and style intact by choosing vocabulary belonging to the same level. So relatively, "tanggapan" and "kasangkapan" will make the document moreformal and literary, but "opisina" and "kagamitan" will make it moreconversational.
In a formal translation, Tagalog of "table" could be "hapag" and not "mesa" (both translates to table); chair could be "upuan" (where one sits) and not "silya" (long accepted borrowed word meaning chair). In an objective evaluation, word choices matter as far as the style and tone of the document is concerned. Or in another way of speaking, it's not always subjective when one deletes "upuan" and inserts "silya".
Insert marginal notes for better appreciation
of Tagalog word nuances
Usually, when an editor erases a word and supplies another, the client thinks that the first translation is wrong. Since it is often difficult for the client to appreciate the reason for the change, a note should always accompany the adjustment. Hopefully the client does care about tone and style. But how will it know the inconsistencies when it doesn't speak the language? Only if the editor cares to explain. And unfortunately, some clients don't even appreciate the marginal notes. Yet to polish the style, Tagalog words used must be scrutinized.