I'm not sure how many per gram of weight, as of course it would vary a bit between birds and activity level, but unless they're out free flying for miles per day (I'm sure Tangie is not lol), I woudn't feed too many on a daily basis to any species who doesn't require a higher fat diet. Keep in mind, for example them eating a whole average size green grape might be like us eating an entire bunch in one sitting lol.
My Pois (around Tangie's size) get a couple or a few almonds per day. Pionus too even though he's twice as big as them. Plus daily anywhere from 0-2 Nutriberries per day. Unless someone is having a birthday, then they get more treats . I think they can probably have a bit more than that without gaining weight.
2 to five almonds a day is fine for a Senegal parrot but anything over that i would not recommend. Since Tangie likes almonds so much, why not use them for trick training rather than just the occasional treat. Also are you sure your mum isn't feeding Tangie more almonds while you're not there?. anyway i hope you and your mums bird are fine.