A word that means "apparently" but with less conviction? [duplicate]

Example:

The circular window was apparently made to match the shape of the sun.

Here apparently expresses doubt, but with a certain level of conviction: that was the intent of the person who designed the window. Is there a word similar to apparently but with less level of conviction? Almost as if the conclusion were a rough guess? Or something that the speaker made up?

Seemingly is what you're looking for.

Seemingly vs. apparently

Apparently:

• Is used when you have read or been told something, although you are not certain it is true. Apparently it's going to rain today.

• Is used when the situation is different than what you thought it was. You know I told you Alice's party was on the 13th? Well, I just saw her and it's apparently on the 14th. How do you like that?

Seemingly:

• Appearing to be something, especially when this is not true. He remains confident and seemingly untroubled by his recent problems.

• According to the facts that you know. The factory closure is seemingly inevitable.

(Quora)

Supposedly:

used to show that you do not ​believe that something you have been told is ​true: Well, the ​tickets are supposedly in the ​mail. ( -- Cambridge Dictionaries Online)

Ostensibly:

"As appears or is stated to be true, though not necessarily so"

'Apparently' as defined in the OED:

"As far as one knows or can see"

...only implies the converse.

So in my mind 'ostensibly' has a larger measure of doubt.