This is just my opinion. As I understand it, Kundalini Tantra practices are about exploring Shakti, the Divine Feminine, the Great Goddess. Shakti is essentially energy; the spiritual power within every existing thing, including human beings.
The universe operates in terms of energy, frequency and vibration. Everything vibrates at a molecular level (Magnasco, 2013). In fact, resonance patterns - or the harmonization of vibrations - have been observed in living and non-living structures of many types (Hunt & Schooler, 2019). Kundalini is sometimes referred to as the Divine Vibration.
So, Kundalini is ever-present. Its an energy that has always and will always exist. It is the energy that our physical and subtle bodies are imbued with. This can be observed in the womb using a fluorescent sensor. Before the development of an embryo or anything physical, there is a spark of light (Duncan et al., 2016).
This light, this energy, this vibration, from which the body is formed, is Kundalini. It is always there, but the physical and energetic blockages that our body develops prevent us from observing or accessing this energy. Like light shining through a window. Kundalini is the light. Our body is the window. And our blockages are like mud on the window which prevents the light from shining through.
Kundalini isn't dormant. It doesn't need to be awakened. It is always there, we just need to remove our blockages, wipe away the mud, and allow the light to shine through us. We can learn practices to release these blockages. This is what a lot of Tantric practices do, including sexual practices.
Sexual energy can be awoken, it can be aroused and drawn up from the genitals, like a serpent rising from the base of the spine. But convulsions and orgasmic waves of energy are not Kundalini. They're experiences of sexual energy, which can be used to clear blockages. That is, sexual energy can be moved through the body to help us wipe away the mud and observe the light of Kundalini. Although sexual energy and Kundalini are linked, there is a distinction between the two.