Does the Cosumi Go site sometimes get the score wrong?
You are right that the top right belongs to White with correct play, but according to the programme Sabaki White wins by one point (because they have a captive). It is conceivable, but somewhat unlikely, that White could make enough errors for Black to win.
The score
Sabaki calculates the score like this for area scoring:

and like this with territory scoring:

The top right
To be on the safe side, I plugged your SGF into KataGo (via Sabaki), and it showed me a ko in the top right that Black cannot win: not only do they have hardly any threats, even if they did, they could not finish the ko in their favour.
The sequence that KataGo found was this:
$$Bcm1 Trying for a ko
$$ +---------+
$$ |..XOO.a25|
$$ |.X.XO.O1c|
$$ |..,XXO4d3|
$$ |.XXXXXOOO|
$$ |..XOXOXXO|
$$ |XXOOOOX.X|
$$ |OOOOOX.X.|
$$ |....OX.X.|
$$ |.O..OOX..|
$$ +---------+

Unfortunately for Black, White simply has to connect with ➅ at a and Black has no way of finishing the ko to kill White. White can just wait for Black to run out of threats and then capture at c and d.
Black’s only chance is if White plays the ko wrongly, for example:
$$Wcm6 White messes up (9 retakes, 13 @ 7)
$$ +---------+
$$ |..XOO36OX|
$$ |.X.XO2OX1|
$$ |0.,XXOO.X|
$$ |9XXXXXOOO|
$$ |57XOXOXXO|
$$ |XXOOOOX.X|
$$ |OOOOOXxX.|
$$ |....OX.X.|
$$ |.O..OOX..|
$$ +---------+


capturing ➅ instead of connecting at ⓫,
threatening with ➉ instead of the deadlier threat at x,
missing x again after Black takes at ⓫ and therefore giving up the ko, so
Black wins by 27 (area) or 26 (territory).