The process of ejaculation does, normally, triggers a release of testosterone as part of the process.
However, the use of anti-androgens inhibits both testosterone and sperm production. So if you are taking spiro or other anti-androgens as a part of your HRT therapy, then there will be little, if any, testosterone or sperm released during ejaculation. The process of shutting down the testes happens pretty quickly upon administration of the anti-androgens. Usually within less than a month and often much sooner.
You will, however, continue to ejaculate seminal fluid which is produced by the prostate as part of the ejaculatory event. So instead of ejaculating a milky white semen, it will be a clear fluid.
So you can continue to have ejaculations without fear of overcoming the feminizing effects of HRT. However another side effect of HRT is reduction of libido, erection, and orgasm.
-Sandy