UK visit visa denied for lack of financial proof. Should I reapply, claiming my uncle as a sponsor? [duplicate]

I applied for a visiting visa (priority) from Japan (where I currently live and work) to the UK for 5 days and it got it denied under provisions 4.2 (a, c, e). I am Ukrainian and before coming to the UK to visit my boyfriend, I planned on visiting my home country and departing directly from there.

The refusal letter says:

The decision

I have refused your application for a visit visa because I am not satisfied that you meet the requirements of paragraph(s) V4.2 of Appendix V: Immigration Rules for Visitors because:

• You have applied for a leave to enter to visit the UK for 5 days for tourism.
• In order to be able to make a decision on whether or not to grant you entry clearance in this category I have taken into account your stated circumstances in Japan, the reasons for your visit, and your proposed travel arrangements. You have declared that you are employed as a Business operations manager and that you earn 1745.00 GBP per month from all sources of employment after tax.
• In support of your application you have submitted a letter from [redacted]. You also submit an additional bank certification which shows a balance dated 2018.9.14. Bank letters only show the balance of an account on one day and do not show the financial commitment of an applicant nor do they show the source of any funds in an account. In the absence of evidence as to the source of these funds I cannot be satisfied that this bank statement is a true reflection of your current financial circumstances and that these funds will remain genuinely available to you for your exclusive use for the duration of your trip.
• I must take into account your personal and economic circumstances when coming to my decision. On the evidence provided I am not satisfied that you have established that your circumstances are as stated and that your economic ties to Japan have been demonstrated to ensure you intend a genuine visit or that you would seek to leave the UK at the end of the limited period stated by you. I am therefore not satisfied that you meet the requirements of Paragraph 4.2 (a) and (c) Nor am I satisfied that the statement presented represents a true reflection of your financial circumstances and that the funds seen will be available to you as stated 4.2 (e)

Future applications

Any future UK visa applications you make will be considered on their individual merits; however, you are likely to be refused unless the circumstances of your application change.

In relation to this decision there is no right of appeal or right to administrative review.

The documents I provided:

• my personal information and my boyfriend’s information, showing that he has a UK student visa;
• boyfriend’s invitation letter and explanation of our relationship (how he knows me, how long we have been together and who I am for him);
• proof of my residence in Japan (a rent contract) and my partner’s residence in the UK (his rent contract);
• my bank certificate with 2700£;
• pay-slips showing my monthly earnings of 1750£ (after tax) and one pay-slip with a bonus stated (monthly total: 3500£);
• employment certificate from January 2017 to June 2021 (when my Japanese work visa is expiring);
• letter of leave from work;
• tour plan;
• bought tickets to Ukraine and to Japan (from the 8th of October and to the 29th of October) and booked tickets for the UK (18th-22nd of October);

The thing that I planned on attaching to my application were my bank statements. I have applied to get them, but my bank (now over 3 weeks) still hasn’t sent them to me, this is why I applied without them. Which I absolutely understand the reason for visa denial.

Since I do not have time to apply from Japan, I plan on applying from Ukraine.

My question: since I doubt I will get my bank statements till then, I thought about stating my uncle as my sponsor, who has sufficient funds and bank statements. This is the quickest way to get the document that seems to be the reason of my denial.

Obviously I plan on explaining why I cannot provide my own bank statements.

Can anyone help me understand if this is a good way to go around this? Is what I plan on doing increase my chances of getting the visa? If so - what kind of documents do I need to show from my uncles side?

Update: I managed to get my bank statements today visa post (after 3 weeks of waiting). Problem is, the amount of money stated on the bank balance certificate (2700£) is different from the one mentioned on the bank statement paper (2200£ as of August the 31st). I had applied for the bank transactions and as I was waiting for them, the amount changed from 2200£ to 2700£. By the time I reapply again, 28 days will pass, so I guess it’s pointless to submit the transactions received?