Stand up straight! Look brave!
(Stand up straight! Do not show fear!)
(In fact, the version with tìtstewnga' is grammatically correct. However, in the context in which Varang speaks it, the original version is justified, even if it bends the rules. She wants to say something sharp and punchy, with good rhythm. 'Ur fkivan tstew! is much stronger than 'Ur fkivan tìtstewnga'. And it's perfectly understandable.)

The trunk of the tree feels solid, although it's dead.

That (tree)trunk sounds hollow.

As for this drink, the taste comes to me as sweet.
(This drink tastes sweet to me.)

Rini's hair looks beautiful.

Rini's hair is pleasant to the senses.

Ralu smells like a hexapede to me.

Ralu smells (looks? sounds?) like a hexapede.

May the food of your holidays taste and smell good.