Is it a problem to use 10W adapter on MacBook Pro touch bar

Well, unless you have 10 or 12 hours to spare without using the computer, using the 10watt charger will not likely produce any relevant charge on the computer anyway. So while it may in a pinch help to give it some charge. In most cases it will take so long, it may not be useful anyway.

Either way, no, there is no danger in supplying less power.

No. there's no harm in doing that, it will just take forever to charge on 10watts. any reason you cannot get a higher rated charger on a regular socket? Like the the one the Mac came with?

It will make charging much faster.

From measurements we took onstage during a show the average power required to charge an 'in-use' MBP turned out to be 13 watts, the Macs were running light tasks and no email clients were active. Peak power required was 42 watts per machine. We built our own rack power supplies that could be and usually had their power envelopes monitored by circuitry in the rack.

Of course 'in-use' varies a lot.

Find the right power adapter and cable for your Mac notebook - Apple Support

It is in no way dangerous to supply less power than it was designed for to your Mac, it just makes things happen a lot slower.

Did you read the content in the link I provided? Specifically the last two sentences of the second paragraph "You can use a compatible higher wattage adapter without issue, but it won't make your computer charge faster or operate differently. Lower wattage adapters don't provide enough power."

That sounds "problematic" to me.

Your question was "Is it problematic or dangerous to use a 10W adapter on the 13" MacBook Pro touch bar?". Your question is clearly answered in the link I provided. Not providing enough power is problematic.

With screen on but not doing anything they draw about 7 watts, with lid closed about 0.42 watts. When off, about 0.17.

If you're just plugging it in for a slow charge in sleep mode, then yes it will charge up the battery. Slowly but surely.