That is a weird design for a FM transmitter.
The standard circuit at the RF power amplifier output is a OMN to match the output transistor's Zout directly to the antenna impedance (usually 50 ohm), then a low pass filter, and that's all. In simple designs even there is no OMN, but only a LPF with Zin = conjugate of the amplifier's Zout, and with Zout = 50 ohm directly to antenna.
It has no sense and it's not common to complicate the design by first matching the amplifier to the filter, and then another "matching x-former" to match the antenna's Z. The less components you use, the less power you waste in RF losses.
Also is weird to use a BPF after the power amplifier, if its function is to filter harmonic frequencies a LPF is better here.
At last, the audio amplifier + up-converter mixer + BPF resembles more a SSB modulator than a FM one.