Your diagonally-oriented brom will survive - but you really should place broms as close to vertical (the center of their rosette opening vertically) as possible. A non-vertical brom will start to stretch and twist in an attempt to orients its leaves toward the light - if it's very young that might be fine. A more mature plant will end up with the new leaves growing out toward the light and the different planes of leaf growth will not look good.
A non-vertical brom will also not keep pools of water in the center and lateral leaf wells reducing the space for tadpoles (if you keep phytotelmatic breeders).
I use a clear cord designed for necklace making to mount broms. It is slightly stretchy, doesn't decompose in the viv and grips better than fishing line. Using cord frees you from relying on pre-existing notches in your wood - instead allowing you tp pick the best spots for the plants. Here's the product I use: https://www.michaels.com/stretch-mag.../10030784.html