I got 5w6, 3w4, 1w9.
5w6 is easily dominant for me and I have thought as much for a while, though I have also contemplated 6w5.
3w4 seems accurate, as perhaps the biggest reason I work hard and emphasize achievement in my tasks is to win autonomy from others (which naturally requires their recognition and approval). I may be misinterpreting 3w4 though as I have not read a lot about this type.
1w9 makes a lot of sense. It seems to relate strongly to defense of tradition and values (also a typically ISTJ type), which are things I value, though at a lower level.
I would say the combination I got is accurate, though I would welcome the input of others on the matter. As is probably clear, I'm not an expert on Enneagram.
You got it right--your interpretation RE your own temperament whereas someone else might test (at the end, say) 1w9 not because of being traditionally based but because growing up their parents or earliest/ongoing guardians expected perfection and that they play 'sergeant-at-arms'.
As for the 3w4 -- the 3 is exactly as you read/see it.
The 4, however, represents (in this context) a tendency (possibly) toward depression if you are not getting the recognition you need. Again, for your ISTJ type whereas, say, many an INFP who get 4s are usually paired with 5s as they are 'romantics' who think a lot about the perfect mate and such--and those I see on here are often into roses, candles, all that jazz (I can't help it if there is some 'tone'; I don't like chick flicks and bouquets of flowers and what-all).
A generalization of course but there's that.
ADDITION: Riso & Hudson as well as Beatrice Chestnut posit the enneagram more in-depth, esp. Ms. Chestnut with her sub-types for each one, so 5s (what I always use as my ex.) are:
Castle (Imagine the moat for safety).
Totem (Imagine someone doing a lot of networking, more able to collaborate, or certainly more self-preservation oriented, i.e "I'm not a rock; I'm not an island.").
Counter-Type (Imagine the most 'romantic' of the 5s i.e. 'sexual' 5s but not roses, candles, Sweetest Day 'romantic'; rather, 'one-on-one'; going deep; looking for the elusive perfect match--and not necessarily 'sexual,' because the perfect match may be a best friend.
I am a Counter-type 5, and I found my perfect match who is no more perfect than I, but this isn't a perfect world.