Well... a wobble is a very slow vibration in the voice. Like, almost siren-like, it is so slow. That’s usually indicative of bad technique that has basically abused your voice for years. Think of your vocal cords as coming together an incredible amount of times per second as air passes between them… healthy vocal cords do so at a certain rate- 6 to 6.5 cycles per second. If you abuse your voice, ‘push’ and scream as substitutes for good technique, the muscles and cartilages involved start to lose their flexibility (in fact, in some cases, they become ‘bowed’ after years of pressure) – which results in 4 or less cycles per second. The voice is also robbed of its natural beauty after years of being savaged.
It’s not a pretty sound, and outside of potential recurring health issues being the cause, it can indicate a bad singer with a very bad and unhealthy technique.
As for “Heldentenor”- we know that there are seven voice types: tenor and soprano (high male and female voices), bassos and altos (low male and female voices) and mezzosopranos, baritones and countertenors (mid-range female voices, mid-range male voices, and men whose falsetto is so strong that they sing in the mezzosoprano range.)
Each voice type also has sub-types. Think of the sub-types as being like weight designations in Boxing, from lightweight to heavyweight. The roles written for each sub-type are written with what that voice sub-type can and can’t do: huge voices (dramatic sopranos, heldentenors, Verdian/Wagnerian baritones and sopranos, etc) are very large, very powerful, not very agile and they usually sing over very large orchestras and can cut through them like a knife through butter.
Middle-strength voices are usually called ‘lyric’ and they usually strike a balance between power and beauty- they sing over smaller orchestras and have moderate agility. They’re usually the romantic leads. The light voices are incredibly agile though not very powerful and so they often sing over much smaller orchestras.
A larger voice trying to sing repertoire meant for a smaller voice is possible. Singing the role of a –much—smaller voice can be incredibly awkward and not very good for your vocal health. However, a smaller voice trying to sing the repertoire of a much larger voice will kill it. To sing over an orchestra size that is twice (or more) the size that is meant for your voice means you will either a) not be heard at all if you’re trying to sing with your usual size or b) you are going to push like hell and that’s going to damage your voice over the long term.
The damage can range from nodules, bowed cords (and wobble), to vocal hemorrhage and worse.
In the end, operatic singing is a fine-motor athletic endeavor on par with the kind of stress and coordination required of Olympic athletics for other parts of the body. And doing it wrong, just like training other parts of your body, is going to fuck you up. And if you’ve done it wrong for too long, then you’ll get fucked up in irreversible ways.
--- so, long story short

… someone who does that is the last person you want vocal technical advice from.
Sorry. It's a very slow day at work today.