topple
傎 centers on the idea of falling over or being overturned: to topple, collapse, or be thrown into disorder. The given meanings of 'topple' and the kun readings suggesting reversal or going mad all point to a loss of upright stability.
傎 combines 亻 (person) with 真, which likely contributes the sound and may relate to the idea of being upright or true. The exact historical development is uncertain, but the character likely expressed a person falling from an upright state.
A person 亻 beside 真 (truth/uprightness) suddenly topples over, as if even the truest person can lose balance and fall.
For テン, imagine a person toppling over after counting to ten: ten -> テン, and at the count of ten they lose their balance and fall.