Yes offset does not work as I want it to.
The main problem is clipping of the offsetted path. Offset of the cubic Bezier curve is can not been defined by Bezier curve. So the only way to make an offset by Beziers is to approximate the offset curve with cubic Bezier curves. It leads us to do a lot tolerances.
Another problem is that offsetted curve could have self intersections and many loops formed by self intersections. So we have to cut bad loops out. But how can we define which loop to cut of and which not?
I've spent about a month to make it work, now I need to have a little rest from it or my head will blow

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As a quick check you can turn on "Draw clipped path" check box to see problem points and add a little subdivision or simplify the path there.
For example if you add a control point to letter C as it shown in the attachment the offset should be fine.
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This was from root.