Has there ever been an example of flaunches borne “sideways”? That is to say: emanating from chief and base, instead of from sinister and dexter.
Heraldically ‘flaunches’ by their very nature always appear in pairs on either side of the shield - otherwise in the ‘flanks’ of the shield. They, therefore, could not appear in any other position. What you are proposing in the chief and the base would be, perhaps, be blazoned as a ‘pair of arcs’, but as stated above they could never be blazoned as flaunches ‘sideways’.
These are my initial thoughts at three in the morning here in the UK.